How much is Sony currently losing on the Vita and when do you expect retailers to start pulling it off shelves?
It's already started with smaller retailers, and larger retailers have been drastically reducing their Vita section, and in some cases relocating it to showcase other products that actually sell. it's a vicious cycle in which weak sales lead to weaker sales.
the other reason Vita will be discontinued is lack of support. a platform cannot survive off multiplats like Zombie Tycoon 2. I expect Vita will be quietly discontinued after the PS4 gets off the ground.