More on What Al did in Chapter 107
I see some people comparing what Al did in chapter 107 to what Al did in the first anime. And I disagree in fact I completely disagree with the word sacrifice to describe what Al did.
I think Mei might have believed Al was sacrificing himself hence her reaction but:
There is a couple things to pay attention to:
Back in Vol 2 when Ed was fighting Scar, Al lectured him not to give up on life when there is a chance. I don't believe that Al would give up on life that easily.
But as others have pointed out if you look at this page you can see that it looks like time wasn't just running out for Ed (with Father looming by) but Al too. It looks like the blood seal was about to be destroyed.
And another point Al has no intention of giving up on his life. He believes that Ed will save the day and come back for him.
In the first anime with no knowledge of what the gateway was Ed and Al sacrificed themselves to bring the other one back. They didn't know ahead of time they would end up in pre-WWII la la land so essentially they were giving up on their lives to save the other one. This is completely contrary to the message in Vol 2 that this type of sacrifice is not the answer.
In this chapter Al is not sacrificing anything either. He is not giving up but based his actions on complete faith in Ed.
Although I am not 100% sure if it will be Ed who will bring back Al. There are some interesting theories about Hohenheim using what remains of his Philosopher Stone to get Al back. I certainly don't know if after all that hard work Al did to get Ed's arm back I wouldn't want to see him lose it again.
But no matter what, I am sure Arakawa will give us a wonderful ending that will stay true to all the characters.