Have you heard the way HHH puts her over? Her rise is one of (if not the) biggest success stories to come out of the PC and Hunter's reign as head of talent.
Plus they have a lot invested in her. She's been a part of so many "firsts" regarding the women, it'll be impossible to tell the story of "when women became important in WWE" without Sasha Banks and you know we'll be hearing that story retold for decades to come.
I think her leash is among the longest of anyone on the roster. Not 90's HBK status, but someone like Owens for example is way more disposable to them than Sasha imo.
they were invested in Paige too. Sasha isn't invincible