Not saying that (assumably) Bruce is the easiest person to work with (or for), but...
We know Roy Z isn't so much into touring . He's had those... potentially drunk ramblings on Facebook every now and then and, correct me if I'm wrong, hasn't been that much out there, like performing publicly etc. for a good while.
We also know that Bruce respects him a lot and has spoken very highly of him very recently as well.
All these things considered, I'm wonder if Roy's physical ability (and maybe mental state as well?) to commit himself to an intense touring for three months was never 100%, even if that surely was what everyone involved wished for, and maybe the possibility that he won't do it was on the table from the start. Who knows what struggles he might have had on his personal life and I'm fairly optimistic that whatever the situation might be, Bruce knew about it.
The press release specifically mentioning other commitments, including the remixes of back catalogue, lends itself to optimistic thinking that even if Roy won't be joining them on stage, he's still very much involved and the working relationship between him and Bruce remains unaffected.
I certainly hope so anyway. For all I know, it could be... for either way.