This thread certainly didn't go as I expected. First it veered off onto the Scottish independence debate and currently it's exploring the issues around F35. I'd hoped it might follow the OP around how hard it is to do meaningful contingency planning. Heh-ho, I guess that's what happens with online fora.
WRT F35, it's worth being aware that at the highest level of cap planning it's just one component in a programme called Future Combat Air System (FCAS). Currently, there are a number of options in FCAS, all of which include F35, with an associated mix of extended, upgraded Typhoon and contender future aircraft, including several possible UCAS variants.
Nothing, and I mean nothing, has been decided in terms of the future shape and size of FCAS beyond 2030, including the RN/RAF/variant mix - but it is being discussed and planned for at length and in depth by some very serious people. Yes, Defence does try to plan out that far (and beyond) and spends real, significant money doing so.
Much debate on this forum is based on the papers, the telly and what's heard in the crewroom - and that's right and proper (and more than half the point - and definitely the major attraction). However, associated assertions should be made with a due sense of self awareness.
Yours in Defence capability planning,
Sun.
