My guess would be that any future government, especially the current one, is likely to inform us that they've just delivered a very generous SDSR and that they are buying F-35, which is supposed to keep dropping bombs for decades to come. They may also ask why, if the MoD wants a new bomber, are they paying for the new wonder jet and why is so much money being spent on expanding Typhoon capability?
I don't think they would see the logic for a new bomber. In any case, its traditional to wait until the old bombers are defunct and on the point of being scrapped (if not after they have been scrapped) before looking for something new.