melmo, I relaize fleet size disparity between US and UK fleets, and also the matters of numbers/scale on parts support.
Is your concern that the avionics and other accessory bits will go out of production due to demand being too low, and thus parts you need will simply become unavailable, or too expensive to afford?
I won't get into th econimics of whatever joint support agreements via primes and subs are extant, since I don't know what they are.
Isn't there a way for the UK to proceed ahead with the chosen configuration and press on, or is your general argument that it will be far too expensive to do that, from an Operations and Maintenance PoV, due to the comparatively small size of the fleet?