Neh hard to tell... Nintendo generally gets a ton more emulator support than other consoles/handheld. I am assuming its due to them having the most amount of exclusives and perhaps they are easier to hack. Its quite hard to tell whether or not it will be the vita or the ps4 since not enough people care about the vita but it has been out longer so... Eh.

Certainly not the x1 tho since most of its games will be playable on the PC.

It wouldn't surprise me if we got an NX emulator before a PS4 emulator, even though the ps4 should be much easier to emulate than sony's previous consoles, Nintendo emulators came out remarkably quick for the Wii and all being well with Cemu's continued development WiiU too, possibly even the gamecube, I'm not sure how long ago dolphin first became good enough for general use.

Ps2 emulation still isn't really THAT good, atleast not on the level of gamecube, wii, PSP and possibly soon even cemu will overtake it.

None Vita is not popular to have an emulator and ps4 and xboxone you should wait more then 5 years.