I think making Magic head of basketball operations is merely a PR move to give everyone the "feel goods" since they are cleaning house.
I think this is an addition by subtraction since Jim Buss needed to go. I'm not sure exactly why Mitch was let go, though. I think he's a good, if not great GM. He is a bit old school, however, and maybe the Lakers are going for a more analytics guy.
My other theory is that Mitch didn't know how to stand up to Jim Buss, so he had to go too since he lacked spin. Or, even worse, he was a big Jim Buss supporter.
They say Jerry West won't be part of the new regime, which is both understandable, and a shame.
The best case scenario would be hiring an analytics guy and Jerry West. Jerry West is the best for talent assessment and trades. However, I don't think West can be had or if he would cede control over things.