2013 was the best year for Vita? Psh. It was a good year no doubt (Hotline Miami; Killzone; Tearaway) but 2014 stomped all over it.
We got a load of surprise localizations (DanganRonpa; Sword Art Online; Tales of Hearts) alongside the last of Sony support (Borderlands 2; God of War/Ratchet/Sly HD Collections; Soul Sacrifice Delta); some fantastic indies (Cel Damage; Rogue Legacy; Velocity 2X). Plus I live in Europe so we got the leftovers of 2013 localizations :P (Toukiden & Ys).
Seriously though, I don't think any year is going to come close to that one for me. 2012 was a bit of a bust (too many rushed western games); 2013 and 2015 were decent but both had issues (too many lulls in 2013; too many disappointments in 2015).
However, 2016 looks great. The big change this year is that Bandai Namco are continuing on with Vita support (which is nice) and Square Enix are finally releasing games on the console again, like you say. Coupled with some surprised western announcements (Asssassin's Creed; Civ Rev); the remaining indies we haven't got yet (Attractio; Banner Saga; Drift Stage) and the localization houses in overdrive (Aegis of Earth; Trillion; Yomawari) means I'll be playing the console a lot this year, at least.
The only part of your post I don't agree with is the sales part. I think Vita is pretty much done in the west after this year and I still think it's overtracked here. The thing is being pulled from shelves left right and centre, at least here in the UK and I believe it's the same in a couple of European countries. While it's not impossible to find, it's certainly difficult and that stunts its chances of selling to the volumes that VGC is suggesting.