Unless a business case can be made for extending the lease, it’ll be ‘Summer 2023’ they go off lease, most likely meaning a May withdrawal from service.
Given the busyness of LNER I’m sure if enough time and resources were put into it that the business case for a lease extension could be made. Whether the time, resources or willpower to make such a business case are available is another matter entirely.
Of course the DFT and LNER have already tried getting rid of the retained Mark 4 sets once, in early 2021, and we saw how that ended!
This exposes the insanity of the leasing system...
If those MK4 sets are withdrawn early, they will just be scrapped, despite being perfectly capable of running a proper service. Why the rolling stock was ever sold off in the first place is beyond insane...
Being cautiously optimistic, DfT may be playing hardball on this, leaving the decision to the last possible moment to scare the lessor into providing a low price.
Btw, 10% figure is probably overblown for a number of reasons - likely most "savings" will fall on the infrastructure side of things at Network Rail for those big capital projects, especially in the South East. There is also the possibility of reductions in road projects. We also don't know what inflation will be like next year and not every expense will be affected in the same way. The big increases in expense is likely labour, but we will have to see how negotiations pan out regarding strike action...
Worth noting DfT is pushing for more drivers to be trained up to reduce the reliance on expensive overtime working.