I'd say that how the Vita held was impressive considering the handheld it was proclaimed dead back in 2015I'm expecting Vita to be down to about 500k-550k this year which will be a fairly significant drop. We're beginning to see the migration of the third parties that have supported the console well (i.e. Senran Kagura PS4-only; Trails of Cold Steel PS4-only).
Also, there's not really any big games left on the horizon for it. Maybe a few in the early months (DanganRonpa/Super Robot Wars/Accel World vs. SAO) but other than that, the latter half of the year has nothing announced. I'm sure there will be a Gundam game here and a One Piece there but we've always had a number of upcoming games that I thought for sure would've been 100k+ sellers and I can't really say the same for 2017.
Still, there's enough to keep it from a complete collapse.