If MS felt they could only launch 'XB2' a year after PS5 at the earliest, then I would suggest they hold off a few years and try to shame the PS5 Pro, assuming next gen plays out similar to this one.
If MS could launch 'XB2' a year before PS5 Pro, and have extremely similar specs, and the same price that PS5 Pro has when it launches, that could make PS look like they were "lazy" and weren't trying to offer the best tech available.
Better yet, if 'XB2' was a year before or alongside PS5 Pro, and it was actually more powerful, for the same price, that would look really bad on PS mid gen, and could potentially cause a shift in brand sales.
This would also give MS more time to focus on new studios and IP for the XB brand going forward and would allow them to launch with confidence across the board.
If PS5 launches sometime in 2020, MS would be ok to launch 'XB2' by late 2020 as well, as long as they have their first party in order by then.