Such a large cut seems impossible. Guys like Ederson are on 100k p/w base, Alisson is on 150k p/w. There's no way DDG will drop to 100-150k p/w. My understanding is that we get a bunch of headroom from cutting potentially 200k p/w on player wages. So why not do it?
https://www.capology.com/uk/premier-league/salaries/
Forget backups, we shouldn't even be paying our starter 200k p/w.
EDIT
Please do double check my math here, but given the way we amortize contracts, a 200k p/w reduction in wages is the same as a new 25M player on 100k p/w. If we got rid of DDG entirely, then we have a 91M / 5 years to work with.That's some variant of a new 50M keeper on 150k p/w wages.