the whole clubs changing ownership to get rid of a player is a lot more risky than its worth. Who is to say all the players you do want to keep sign the contract? Maybe players will get pissed off at the club for using a loophole to get rid of one of their teammates and collectively decide not to sign? Some players may negotiate better deals for themselves?
I don't think its as simple and viable option or loophole as people are making out.
Players can still decide if they want to play under the new ownership or not. That is simple and realistic. Is that a good thing? The PFA would think so, club management not so much.