Vats wouldn't work with ANY real-time multiplayer game, for obvious reasons.
I can't think of many single player games I'd want to see it in, either.
Like others said, fallout was built for v.a.t.s and that's where it should stay.
Besides, I never used v.a.t.s anyhow, and the game was already amazingly easy to clear through (on every single one of the hundred different locations in the wasteland)
It's mostly a gimic, and a method of implementing the original action-point based combat system used in fallout, fallout 2, and more closely in fallout tactics. It's useful for people who are crippled by the lack of accuracy with a console based controller, to clear the gap between capable and incapable fps players, and to give you an edge over lag, or just bad circumstances at the time.
The system wouldn't work outside of fallout, purely because it's a stat-based system. There are perks, a whole variable table of calculations to be made on the fly, that wouldn't exist in a game that didn't have a character who had individual skills, and perks, to affect the % to hit.