Considering PS3, PSV, 3DS, Wii U, PS4 launches in Japan I think that scenario of companies moving all their projects exclusively to NX is rather unlikely.
Especially when they have code and assets to reuse but maybe they will make PSV/NX/PS4 release (at least I'd do it to slowly start building userbase there).
Hmm plus no matter how much we like our Vitas we will sooner or later (2-3 years) have to make a decision too since Sony is not going to release Vita2.
Either we will migrate to NX or go ios/android
At least all rumors point into direction of solid 720p screen and above Wii U performance in portable form so in spirit it should be closer to PSP/PSV than to Nintendo gimmick instead of solid hardware philosophy.
Actually there's another choice that i hope will be well made and successful
https://www.youtube.com/watch?v=IrqycNgukCg
especially considering that most of the vita(and console in general) games and similar are ported to steam...