I'll go out on a (short) limb and say Khachanov. Not as obvious as are Thiem at the French or Zverev/Tsitsipas, but he's got a very high ceiling when he's playing well.
Anderson is older than Rafa and my guess is that after this latest injury, he's pretty much done.
Good call on Khachanov - he can play at a really high level. His buddy Medvedev also has a really solid game, and I could see him advancing really far in the US Open.