It would shift the dynamic too much.
A lot of Little Mix's appeal (deliberately or not) was on the surface-level "sisterhood" they seemed to have. The trio could definitely still get away with portraying that. Jesy wouldn't be believable, at least not now.
The Geru / Spice Girls split, however fraught, never became as publicly nasty as the Jesy / Leigh-Anne / Minaj fall-out.
Robbie / Take That was a little more hostile, but it took them 15 years to set it right, a lot of very open and public dialogue. And I don't think Take That were ever as heavily reliant on the "bezzie mates 4ever" card as the girl groups were often forced to be.
It's also worth noting that most of the other pop group implosions were due to egos and trivial personality clashes. They could be papered over with a "we're adults now". The blackfishing however is a much more sensitive and core issue to walk back from. Even if she somehow won the girls over, I can imagine some of their fanbase protesting without Jesy accepting her problematic behaviour, which there's been little sign of.