I think it would be a really cool idea that once you hit 50. There can be "raid" fights. Where you could have lets say up to 8 people in a fight in order to beat a very toughed ranked enemy and maybe some friends to go with him. These would give you gear that cant be matched by anything else. But this gear should not be able to be sold or anything.
Would just be fun to give something for the lvl 50 players to do. I dont think raising the max lvl would be a good idea yet. Maybe in the future.