This is pure speculation about something that will not occur. The X-Pro2 will have the dual purpose viewfinder. Without OVF it's not an X-Pro. I would not buy it.
Yep, I have a pair, too. I hate changing lenses in the field (since the advent of digital, no problem in the good ol' film days). My two X-Pro1s would like to be considered classics and not electronic trash.
As I remember, most of the Nikons, film and digital were of one size except the F3HP, which took a larger one. But . . . why not just buy a Fuji? Maybe they're a couple of dollars more expensive, that's all. I got two +3 at either B&H or Adorama.