Okay, regarding the Stephen Moffat news: what amuses me among is that both the majority of squeeful enthusiasts and the minority of mournful detractors responding to the annoucement seems to expect/hope/fear Mr. Moffat will start his tenure as Doctor Who headwriter/producer by making basic changes. Seriously, I doubt that. Some changes, certainly. For example, based on his own DW episodes so far, I think we might get mostly standalones and not arcs. Also, since he's an excellent plotter, there probably won't be a deus-ex-machina solution for the season finales. (Assuming he'll write said finales, which is common but not always the case with headwriters.) But, say, a turnaround from one to three alien planets per season max to mostly alien planets and just one or two earthbound stories? I don't think so. The only New Who Moffat episode that didn't take place on Earth so far was Girl in the Fireplace, and there you could say he cheated, because of course all the events surrounding Reinette did take place on Earth. The Empty Child/ The Doctor Dances and Blink all took place on Earth. Now given that Moffat basically was given carte blanche by RTD for all his episodes and thus could have placed them in outer space if he had wanted to, I'm assuming this says something about his own preferences.
(Sidenote: incidentally, while Old Who in its decades of tv history had eras where it was a different alien planet every week - the Tom Baker years come to mind - it also had eras which were far more earthbound than current Who. To wit, the Jon Pertwee years. So the argument that one is more typical than the other for DW in general never held much sway for me.)
Then we've got the Doctor/Companion relationship question. I've seen a lot of "yay! No more love stories between regulars!" and some "oh noes! our romance retconned out of existence!" Now based on his own episodes, I don't think Moffat ships the Doctor with any current companion, but this is the man who, in his pre-Rusty, pre-New Who sketch for Children in Need, The Curse of Fatal Death, had the Doctor being engaged to his companion. (But in the end leaving her for the Master. For reals. But hey, the Master is played by Jonathan Pryce and he finally proposes!) So I wouldn't be too sure that once he creates his very own companion, he won't end up at least playing with subtext. Especially if he wasn't kidding about his views on women. I mean, I personally hope for more of the type of relationship the Doctor currently enjoys with Donna, as I find it very appealing and think that Rose and Martha have both demonstrated that explicit romantic feelings between Doctor and companions on this particular show are dead-end roads and severely limit the companion; if it's presented as mutual and a love story, the companion in question is doomed to either leave or die because marriage or the sci fi equivalent thereof simply isn't in the cards, and if it's presented as one sided, then you split the audience into partisans, some of whom see the Doctor as a calleous bastard and some of whom see the companion as a clinging stalker. So yes, I'm all for no more romantic subtext between the Doctor and whichever companion Moffat will come up with; I'm just not sure that it's self-evident we'll get this just because he's not RTD.
Unless
londonkds is right and Moffat lobbied for Jenny's survival in The Doctor's Daughter because he wants to use her as a companion in season 5, in which case he can play out a strong emotional relationship between Doctor and companion without romance being even a question. On the show, that is. I know fandom, and incest is the new black.
(In regards to past companions, I am fairly certain Moffat will manage to democratically annoy the more fervent shippers of all camps. There won't be any more Rose references. There won't be any more Martha references, either, unless she actually is in an episode, and if you think Stephen Moffat will make the Doctor suddenly declare his undying love for Martha and utter repentance for not having done so back in season 3, you're dreaming. And if a comment I saw at a DW community is true, he already potentially pissed off Two/Jamie 'shippers by declaring Fraser Hines can't act, or something like that, so one of Old Who's treasured romances is slighted as well. *veg* Apropos past companions, since RTD always said he wouldn't touch Jack's two missing years because he regards them as Stephen Moffats territory and only Moffat has the right to write about them, I'd appreciate him actually doing that, whether on Torchwood or on Doctor Who.)
Companion gender: yes, Moffat invented Jack Harkness. No, I don't think that means he'll give the Doctor a male companion. He might give him a female and a male companion, but we haven't had that since Five's day (where the combination was two female, one male companion at the same time until the last two episodes), and the current BBC clearly regards the Doctor/One Companion formula as the winning one. My money is on only one companion, female, for at least the first of Moffat's seasons. (Speaking of the Five era as the last example of reglar male companions for entire seasons, in the Moffat-written Time Crash, Ten asks after the two girls, Nyssa and Tegan. The two boys, Adric and Turlough, are strangely unmentioned.)
Let me see, what else is regarded as RTD-typical that I don't think Moffat will change? Well, there is the Time War and the whole last-of-the-Time Lords angst, but you know, my bet on that is that either Rusty himself will resurrect Gallifrey and the Time Lords at the end of his tenure (either at the end of this season or in the last of the three specials he'll write for next year), or they will remain gone during Moffat's regime as well. Why? Because if you do mostly standalones instead of arcs, you're not inclined to change the status quo, whether said status quo is last-of-the-timelords or the old rebel-among-many-timelords, on such a fundamental basis. So if there is a fundamental change, it will be one RTD makes before he leaves.
As for a regeneration: that probably depends on David Tennant. Who is thoroughly enjoying his current job and if the Confidential he did with Moffat for Blink, where they both geek out about their favourite Old Who monsters and most beloved scary scenes, is any indication, gets on famously with his fellow Scot, but sooner or later will want to move on. Personally, I hope he'll beat Tom Baker's record, as I love the Tenth Doctor, but ototh most of the other actors who played the Doctor went by Patrick Throughton's advice that three seasons is the ideal time span. Who knows? If I have to guess: he'll probably stay for at least the first of Moffat's seasons because a transition of headwriters rarely comes with a switch of leading men as well, especially if Moffat also brings in a new companion.
Lastly: so far, I've loved every single of Moffats New Who episodes, but he wouldn't have been my first choice for next show runner. Not because of interviews past (I think the only tv writer who hasn't managed to annoy me sooner or later in interviews is Joss Whedon; which isn't to say I'm not annoyed by other Whedonian things, nobody is perfect, but the man does have a talent for being unfailingly witty and engaging in conversation and hasn't gotten into silly flame wars with fans (Aaron Sorkin), into diatribes about historians (JMS) or into you-just-don't-get-it-people lectures (RTD). Mostly for the same reason why I'm rooting for Paul Cornell's Human Nature/Family of Blood over Stephen Moffat's Blink for Hugo this year, I'd have preferred Cornell as the next headwriter. He does in-depth character pieces, Moffat does brilliant scary standalones. The former attract me more than the later, but then, I favour Dickens over Thackeray, and Cornell & Moffat always struck me as the Dickens & Thackeray of New Who, respectively. But if we're to have Thackeray, then Thackeray it is.
One more prediction: because I've seen this happening in every fandom with every showrunner, I prophecy the following type of reactions in 2010:
"Yay! Hail Moffat! Finally!"
"This is soooo much better than any episode during RTD's time." *followed by long rant about Rusty instead of a review about the current episode*
"How dare he? The Doctor never used to do X or say Y. THIS IS NOT MY DOCTOR."
"Z is my favourite companion ever." "Z sucks. I hate Z! Z is such a Mary Sue!"
"Um, this episode is so not Blink/The Doctor Dances/ Girl in the Fireplace. Moffat has jumped the shark!"
"Wow, that was awesome. How dare anyone question his brilliance now?"
"OMG, I wish Moffat would just SHUT UP. I hate his interviews, his podcasts, and probably the shop who sells that ugly sweater he wears in the Confidentials."
"....that was so heterosexist." "Continuing gay agenda much?"
"...did you see that just happened in the last episode! This is so proof that Romana/Rose/Martha/Jack/The Master/The Rani/*insert other character of choice* will come back!!!!!"
"I'll never watch this show again! No, really! I hate every single bit about it, I post nothing but rants every week, and I will never watch it again. Except when a new rant is due, next week."
"...there was New Who before Moffat?"
"Rusty, all is forgiven. Come back now!"