I appreciate all the comments, thank you.
The difference between what may lay ahead and previous manufacturer ‘exits’ from the Motability scheme, is software.
Silent updates and OTA patches are so frequent these days that limping by to the end of a lease period is unlikely to be practical now, and depreciated software would become an open door to thieves and hackers.
I’ll let you know what Motability Operations say when / if I get a reply to my letter (just posted).
John