One issue here: what will be given up to retain Trident? At the very least, current planning will lock-in SDSR10 force levels. If (as Mr Boffin suggests) there is no plan to buy 138 F-35s (in which case someone needs to notify the JSFPO), the idea of a replacement for Tornado becomes unrealistic, particularly if SDSR15 restores two carriers; a smaller F-35B force will be largely devoted to maintaining the sea-based capability.
Not only that, but Trident will squeeze out the systems needed for its own survival - see our MPA thread.
It's also worth noting that the USN can't afford Ohio Replacement without a direct raid on another service's budget.