"Ok. Steve it is then."
As far as I'm concerned, by failing provide something usable himself, he waived any right to ownership or interest, and everyone was free to apply whatever placeholder label they want when they need to refer to him. It's no longer any of his business. He opted out of having any say in it.
In other words this is not a Dayta vs Dahta situation.
I'm lucky in that I have no reason to refer to him for any reason that doesn't involve his music or performances from the time when he was still named Prince, so as far as I'm concerned, for all of those references at least, it's still valid to refer to that artist by that name, and it doesn't matter that some other artist exists at some other time. It's a Prince album, a song written by Prince, Prince played pretty great guitar in a special one time, etc.
I bet he still collected royalty checks that Prince earned and retained ownership of all his posessions and copyrights even though he was supposedly not Prince any more. Oh I guess Prince, while still Prince, had the right to gift everything to the new person same as to a child or anyone else, but then that comes with a pretty big tax which I bet he didn't pay at the time of this massive transaction.