They will not axe Hunter and Nick, and Stephanie could possibly come back. There is evidence that shows they tried to keep Vince away and stop his evil-ness and that will be argument enough from a business standpoint regardless of if they knew or not, which we will likely never fully know, however the timeline of events does point to them finding out after the fact and forcing him to retire when things first came out.
They'd also want to keep them for the simple fact of being able to run the business efficiently because who the fuck else would, Endeavor couldn't run it themselves the same way they couldn't run UFC without Dana White. They aren't stupid and reckless, but they're still a business.