I imagine they'll make a PS4 version for the West regardless.
However it puts Bamco in a bad spot going forward. They really need a "OMG! It's amazing" Tales to get all the good will back. Not sure if they have it in them.
I don't really see the alarm or anything. Why pretend that Tales is a series which hasn't historically had its ups and downs? Look at the sales for all the mainline Tales across 5 year periods. The titles which sell the most tend to be the first new one on Playstation platform, before the sales start to decline again. ToZ on PS3 is far from the worst selling Tales game, and by the time it's done selling, it'll pretty much be above average when compared to the final couple of PS2 Tales.
ToD - 829,618 (PS1, 1997)
ToP - 550,394 (PS1, 1998)
ToE - 669,248 (PS1, 2000)
ToD2 - 762,861 (PS2, 2002)
ToS - 322,779 (GC, 2003)
ToS - 394,312 (PS2, 2004)
ToR - 596,493 (PS2, 2004)
TotA - 556,465 (PS2, 2005)
ToL - 342,779 (PS2, 2005)
ToD - 367,998 (PS2, 2006)
ToH - 261,751 (DS, 2008)
ToV - 204,305 (360, 2008)
ToG - 212,769 (Wii, 2009)
ToV - 408,171 (PS3, 2009)
ToG - 338,628 (PS3, 2010)
ToX - 670,182 (PS3, 2011)
ToX2 - 459,384 (PS3, 2012)
ToZ - 346,430 (PS3, 2015) <-- Still selling