Internally they are probably looking at 2017 in Japan and TBD everywhere else.
It's interesting that a major reason the first-party library in 2017 looks scarce to a lot of people is that nobody believed Xenoblade 2 would actually come so soon. I don't expect it either, certainly not in the west, although it's worth bearing in mind that as far as localization labour goes, it isn't directly competing with the crunch for any other localization-heavy games we know about, like the usual all-hands-on-deck projectsAnimal Crossing (I doubt the mobile game will have as much dialogue in it as a standard entry), Fire Emblem (Echoes will be out the door in May), occasionally Paper Mario.
Even so, the first public showings of a partly localized Xenoblade X came 6-8 months before the game itself, from the Treehouse Direct in April 2015 where they first committed to the names of planetary regions and Skells instead of Dolls, to a trailer with English text (but no voices) at E3 that year. That might be a handy reference for clues to the production/release schedule in the west. And from it, it's not unthinkable from what we've seen that we'll get it by the end of the year, just not at all expected.
I think our preconceptions of Xenoblade as perpetually delayed come from a number of things:
- The experience of the first Xenoblade's belated western release;
- The three-year wait from the January 2013 unveiling of 'X';
- That a two-year gap from Xenoblade X to 2 seems implausibly short.
Concerning the third of these, I think it's safe to surmise that pre-production/concept/design/engine work could have been done concurrently with the late stages of X and the asset/environment support for BotW. And I expect there was less involved in those preparatory stages than the volume of labour in the early development of X, a staggeringly ambitious world (and tangled, overbaked plot) built up from scratch during a difficult period of transition to HD.
