Q-A,
I've seen Harrier II+ in build, and reckon even with acoustic vibration they have a long life !
Quite a lot beefier than GR9 etc.
There are also monitoring systens such as EUMS, and I'm quite sure RR would provide support with zero-lifed engines.
I am out of the loop now, the only UAV's I dealt with were Jindeviks, but I get the feeling there's a generation or two of Naval Pilots to go before we put our lives and country entirely in the hands of machines.