New StreetDecks & ADL Enviro400s - X-lines fleet changes
I'd assume that any changes will have to be okayed by the powers that be - either local authorities or central government who will probably turn round and say why now and for what reason.
I would hazard a guess, whoever is responsible for subsidising the services has looked at the last pre-COVID timetables and said "I want that one", so thats what they'll get