Unless they somehow see Collins suspension as the sign of a lost cause, which I doubt very much, they have to keep him. Just too good a player, and we've seen in the past how lack of depth on the O-line can cause big problems. Steele has done a very good job filling in, but he is not as talented as Collins.
As for Gallup, he's in the last year of his contract, and Wilson can play, but again, depth is important to maintain. Like someone else said, if someone offered something big to trade I would consider it, but otherwise I believe we should keep Gallup.
Bottom line is we don't want to do anything that could sabotage what could shape up to be a very good season, and depth is almost always a factor in successful teams.