I think a reunion in honor of Syd would be awesome, but I highly doubt it will happen. I think Waters has a tour planned for next year (his show is amazing by the way, go see it) and I'm sure Gilmour's doing his own thing. As for Wright and Mason, I'm not sure what they're up to. But if it were to happen, I think simply a performance of the Wish You Were Here album, as well as a few early Syd songs, would be appropriate.
As soon as Roger finally releases an official The Wall Live DVD, then anything will be possible. ;p