Nothing at all. I don't own PS Vita and I'm not thinking about getting one. The most sensible for me would be not doing any GTA games for it.
An egoistic attitude.
I would love to see a non-canon post-apocalyptic zombie stealth survival horror spin-off (in short!) set in Los Santos, with a place for The Last of Us and The Walking Dead references. Plain and trivial as crap, but potentially fun nonetheless. Imagine how exciting would it be to fight for every piece of food and ammunition, to travel from one post to another, and slink upon the hordes of the monsters.