I still think it’s too early to say about the people saying they will only stay on JPN or everyone only moving to JPN . As someone who has worked in Retail you get that all the time . “Oh I am never shopping here again” or “you’ve lost yourself a customer” but then the very next week you will see that person actually come back . So how many people truely mean it is actually something to take into consideration .
You will know the signs of it failing because 6 ships would become 5 then 4 ext . There is also potential on the PS4/Switch if SEGA can get that out for them too resulting in a potential wave of new players but it depends also if they will share the same servers as Microsoft as that would ideally mean only having to run 1 set of servers as opposed to many for diffrent consoles
They also should allow Europeans to be able to chuck money at them as yah it may not be as large of a market as America but it’s money non the less . They need a way for players to be able to buy AC or premium or any packs without region lock like say having a section on their website for topping up AC or buying said packs . Because that could also be a selling point for this game
Idk like I think it will survive till the end of the year but again it really is going to depend on a lot of factors how it does the years as they go .