I'm a bit worried by andy's comments on this opportunity. I'm hoping Lemdl is coaching him in the mental approach to winning, as discussed on the impress coaching blog.
Do you mean the opportunity of Mayer going out, or the opportunities long term for Andy now, since getting his first major? Either way, never worry about anything Andy says. It doesn't mean anything. In terms of Mayer going out, sure, it opens a door, but first matches after a few days of not playing can be jittery affairs.
If Andy went around saying things like 'I'm now going to win every match I play', I would be worried to be honest, because the fact is that he won't, although these days players have to be on great form to beat him, or they have to be plain annoying like Raonic lol. Frankly Andy is too respectful of the others nearest him in the rankings to go around blowing his own trumpet too much. That's what he has fans for lol.
It seems clear to me that it hasn't quite sunk in with Andy that he has won the USO. He knows he has, he has the trophy to prove it, but I think he can't quite find the words at the moment to express how that feels, and certainly can't say with 100% certainty how that will help him in the future. They key, it seems to me, is how you play as a result, and how far you believe you can go in he game. Andy has clear goals now for where he wants to be, goals he might not have thought were possible before. That in itself tells me that he has belief, he knows now what could be possible for him. That is confidence enough for me.