Public perception is now that we are out of Afghanistan and Iraq (yes, I know) so defence is not an issue. No politician is likely to commit ground forces to any more large ops until they have to by necessity as the public are fed up of it. We can continue to send Typhoons to intercept Russian bombers, events which will become less newsworthy and so will slip out of the public eye.
Retired generals, admirals and air marshals can continue to stamp their feet as much as they for all the good it will do, and the armed forces will slowly reduce in size until they are little more than a home defence force with an aircraft carrier to show the flag elsewhere, and a proportionate contribution to NATO's RRF. Which is fine as long as that is all they are there to do, but if any politician feels we should be playing world policeman, then he or she will have to divert resources and funding to the armed forces from elsewhere. Which will never happen until a Kilo-class surfaces next to the Palace of Westminster.
On which note, even a home defence force has to be able to watch over its own sea lanes.