They are probably getting rid of these because, from what I hear, Sony is getting ready to launch a PS Vita Slim this holiday. I heard it from someone at Best Buy who heard it from a Sony retail manager type person. Someone who works between Sony and Best Buy. I don't know if they would know, but they said it'd have an HDMI out and longer battery life, maybe a higher def screen. I googled and it says there's some patents for one like that.
This is a great device and for a great price, esp. if you are getting a PS4. But with rumors of a slim popping up, I wouldn't buy this one right now since I'm the kind of person that wants the newest version of whatever. Too bad I already bought one.
The patents are for the dev model that already exists.
[Update] We've heard from a reader familiar with the Vita's development hardware that this could be the patent application for the devkit.
Also going off what we've seen with the PSP... I wouldn't expect a super awesome new version.
PSP 1,000 - Base Model.
PSP 2,000 - "Slim", mechanical UMD tray removed (because they broke down / had UMD shooting out complaints), removed "Pandora" battery on most models, smaller battery.
PSP 3,000 - Slightly improved screen (had many issues), built in mic, PS button, supposed worse battery life (due to the screen).
PSP Go - Need I say anything?
Anyway, I don't see the Vita getting revised and released around the same time as the PS4, since it will get killed in sales regardless. Sony might revise the system down the road, but most of the PSP updates weren't really revisions as much as fixing issues like the pandora's battery.