Not gonna happen. Stamina is already breaking the devs rule of "all classes are equal" and it's sheer purpose is to buff gunner.
Putting your suggestion into the game could result with engineers taking the gunner stamina traits, making gunner less viable. And also, it's the direction that devs in general don't want to move*. You have to give better reasons than "I wanna!", and you know it.
* I mean, going away from "only tools" thing to perks and stuff