Personally, I think Al's going to die. It's the only ending that makes sense.
1) There is no way that Ed and Al are going to regain their bodies. Not only because it doesn't go along with the "mood" of the series, but it completely goes against the whole theme of "equivilant trade". They've been shoving the principle of equivilant trade in our faces from the start, and for them to just find and use the philosopher's stone to get their bodies back is just kinda... cheap. Not only that, but they did something wrong. They got punished for it. To take the punishment back gives the message "I can mess with nature as much as I want because the results won't be permanent".
2) If they aren't getting their bodies back, it would be no problem for Ed to continue living the way he is. But Al can't survive as a suit of armour. Without the ability to use his senses, he'd be cut off from humanity and eventually lose his. He's been suffering like that for years, commenting about how much he wants to touch his brother again and angsting over how he might not even exist. It's just merciful to put him out of his misery.
3) For the theory that Ed would die to give Al his body back, that most likely won't happen. First of all, we already know that Ed won't do *anything* for his brother. He wouldn't kill all those people to create the philosopher's stone. On top of that, Ed doesn't strike me as a suicidal person. He's a good alchemist, and he knows it. He's a big help to the public, and he knows it. He knows he'd do more good for the people alive than dead.
4) All the character deaths in the series have been preparing Ed for the eventual death of his brother. Every time someone dies, Ed lost it. Notice Al doesn't have as intense a reaction as Ed does. This could be linked back to the fact that Al can't really "feel", but I think it is to make us focus on Ed and how he reacts to death. He will slowly come to accept the fact that people close to him will die, and he will, in the end, accept the death of his brother.
5) The philosopher's stone is not of nature. It is not meant to exist. Being that now Al is the philosopher's stone means Al is not meant to exist.
So there you have it. Anyone else want to throw in their $0.02? I'd like to hear other opinions or theories.
Crossposted in my personal journal and fmalchemist