The PL wouldn’t really be enforcing ‘old rules’ in such circumstances, they would be applying the relevant rules that were applicable to the three year accounting period up until the end of season 23/24. Like when a criminal is sentenced in correspondence with the law that was in place at the time of the offence, and not in line with the law at the time of sentencing.
The ‘not fit for purpose’ argument is really weak when the clubs vote in favour of the rules themselves. And this works both ways, whether the clubs decide to change the rules ‘from now on’, or if they decide to change the rules retrospectively so that they no longer apply to the three year accounting period that will conclude at the end of season 23/24.
As long as we are still in the league, I’d be happy to see the rules changed retrospectively, so that there are no more point deductions at all. But I think it’s more likely that any rule change will be ‘from now on’, meaning there will be further points deductions being dished out under the current relevant rules at hearings being held this time next year.