So after some mindless clicking around, I managed to find out (I know, a little late to the clue bus) that Kripke is handing over the reigns of Supernatural Season 6 to Sera Gamble and is in the process of developing another awesome new show for Warner Brothers.
Based on the last demon hunting show that planned on ending at season 5 with its hero jumping into a portal of doom to save the world whose creator left the reigns to his trusted female producer, we can surmise the following:
- Kripke's new "project" will be called "Castiel." It will be about an angel investigation company being run out of the Van Nuys warehouse.
- Sam will be mopey and disaffected. Dean will be so happy to have him back that he doesn't notice at first. (Yeah, I know that one is a forgone conclusion.)
- At some point Sam will begin to have an unhealthy, illicit affair with his creepy stalker, Becky.
- There will be a musical number where Bobby inexplicably decides that leaving Sam and Dean to their own devices will help Sam learn to function again.
- Dean will become engaged to Lisa only to leave her at the altar because of some evil future vision of himself. Sam will bitch about the ugly tux Dean put him in.
- The Ghostfacers with start to stalk Sam and Dean, and try to bring them supernatural trouble.
- There will be a season 7. In it, Becky will suddenly gain coolness, and Sam will fight with Dean and Bobby about her riding in the back of the Impala helping them hunt. Bobby will have a complete personality change and remind the boys that they should be depressed all the time.