Nothing has been announced, as @wmcforum says, there’s speculation arising from a survey about the mileage and Motability would have a good idea how many cars returned to date would exceed any proposed limit and what effect that could have financially. I suspect they will be looking at ways to reduce their costs and this is an obvious starter.
The most intelligent guesses at what will be imposed come from clues Motability have given but even those are just supposition.
All we know for certain is that Motability plan to offset as much of the planned VAT and IPT rises by cost savings wherever possible. Anything beyond that is speculation for now.
My guess is we won’t know for sure until late May for a July 1st implementation.
I'm Autistic, if I say something you find offensive, please let me know, I can guarantee it was unintentional.
I'll try to give my honest opinion but am always open to learning.
Mark