The odds are low they would ever tell the old stories. The new showrunner would hire writers and directors, and the first thing they want to do is put their own stamp on the franchise. That means they will try to create new characters (often times they will be self-inserts) and then they will have new characters beat up / kill / destroy all the old characters to build up their credibility. So you might get something like a story centered around a Med'an type character who is mixed blood and in the first episode he kills Grom Hellscream, Thrall, and all the warchiefs solo.
It would be up to the showrunner to step in and strictly control the writers to prevent that sort of thing and keep the writers and directors on the actual material. But that almost never happens.