WEBF,
Sadly, what you fail to be able to do is understand we cannot afford to do all the things you wish, properly.
We can have a Trident replacement but the SSN fleet will be 7 boats and you cannot get any MP aircraft.
We can have new carriers in 2020 but we have to lose those we have now and all the aircraft that could fly off them. Top that off with turning the RN into a laughing stock with ship levels below that of the Canadians or Australians, if rumours are to be believed.
You are correct that no one can guess the future threat however; we are creating a military that can deal with none of the ones we project as likely!
Cheers
BHR