Hey don't underestimate the lifespan of a carrier.
The HMS Hermes was a WW2 era Centaur class carrier laid down in 1944, redesigned to CATOBAR in the 50's, finally completed/launched in 1959, converted to STOVL in the 70's (lets hope this cost saving measure has no ill effects), served in the Falklands war in the early 80's (oh ****), sold to India in the late 80's, upgraded in the 90's, and finally decommissioned from service in March of 2017 as converting back to CATOBAR was deemed too expensive.
So if the Queen Elizabeth lasts 73 years too that would be great (as would an upgrade to CATOBAR, as it should have been in the first place).
Was talking about the planes not the carrier itself.