Yeah I think the hopes of Switch getting all those Vita devs/games is pretty much dead in the water. Switch releases are going to disappear pretty quick in general though.
Yeah, hold your horses there mate. Koei-Tecmo didn't support Vita properly either until 2013 which is when Omega Force finally started porting their games across (and Toukiden released). Before that, it looked bleak. Switch isn't even out yet.
Saying Sony gave it two years of first-party support is very generous. I don't know how many first-party games were greenlit after the Vita came out, but I know it's not many. I'm sure people will disagree, but I see Killzone Mercenary as the last big first-party Vita game to deliver on Sony's promises. The game came out in September 2013, not even two years after the system's launch. It seems pretty likely that the game was greenlit before the Vita came out and the first indications of bomba came in. I own the thing and liked it originally but it's been frankly insulting to be a launch day buyer. Clearly it was a good move for them and business is business, but I'm in no rush of supporting them again.
(Just before I type this, let me preface it by saying I was hugely disappointed by Sony's support of Vita)
I don't think any major first-party stuff was greenlit following the console's launch. Killzone was well before it released; and Freedom Wars was in development for 3 years too (so 2011, prior to it releasing). The only possible exception is Oreshika.
I'd say Freedom Wars was Vita's last big game though, and that came out mid-2014, so about two and a half years after.
To be honest, Sony's strategy was just a lower-effort version of Nintendo's. Aside from Zelda, Nintendo had effectively withdrawn from WiiU development/publishing by the end of 2015, with 2016's releases being lower-key stuff. That's similar to Sony who were pretty much done by late-2103 and just had lower-key stuff after that (HD Collections; Borderlands etc.)
Admittedly they pulled out sooner, but the effect was largely the same, even down to both console manufacturers picking at the carcasses of their dead console to support their others (i.e. Vita -> PS4 ports and WiiU -> 3DS/Switch ports).
I wonder how fast Vita sales in Japan will dry up after the Switch launches. Obviously the Vita will have a stronger library for some time, but if anyone is buying the Vita still because it's the strongest handheld that can support console-like experiences, a lot of those sales could "Switch" almost immediately.
Vita sales were on the decline long before Switch releases or was even revealed. 2016 was the first year Japanese sales for the console dipped below 1m on Media Create (850k) and it's pretty clear they were due to decrease substantially this year too. Minecraft can only do so much after 2 years on the market.
