How do you know that? Nioh, Persona 5, Yakuza 0, Yakuza 6, Kingdom Hearts 2.5/2.8, Ni No Kuni II all have a chance of coming to Xbox. In this day and age games that aren't 1st/2nd party just don't stay exclusive.
funny, because you just named a load of games where it is likely they will all stay exclusive. there are loads of japanese games that will stay on PS4 only because they won't sell on xbox