Barring any unique outside intervention, these six players should be ready to compete for the title:
That looks like a damn good field. Zverev should be hardened to slam surroundings and Thiem to hard court surroundings by that time, so I'm fully banking on them being a factor. Kyrgios is a wildcard, I am merely hoping for him to simply be mentally checked in.
I don't think any of Djokovic, Murray, Wawrinka, Raonic, Nishikori will have a WINNING role after such a long-layoff, but they might anger these guys a bit or tier 2 individuals.
I think that group of 6 looks like a solid estimate though and a solid top field. Can't be too sure about Del Potro.
Kyrgios? Def not! he just has brief flashes of his top game.
Az? So far blech in slams
Dimi? More realistic choice but why USO crap performance after winning Cincy?
Thiem? Like him a lot but not so great on HC and also not so great in slams
Djok Waw and Murray all deserve places ahead of these guys