On the subject of the RNFSF (Fixed Wing), the recent redesign of the RN website (which also deletes carriers and removes virtually all references to the Harrier - shades of George Orwell) has removed the RNFSF(FW) page (it was listed under RNAS Yeovilton). However, a quick look on Google suggests that they did survive SDSR as
these pictures prove.
Pre SDSR RNFSF(FW) parented all fixed wing RNR Pilots. If it still exists then the infrastructure exists to support RNR Harrier flying or other options (see above ideas) - we would just need to borrow someone's Harriers. FR20 does advocate an expanded RNR Air Branch.
On the skills issue, I would point out that the more you look into it the more there is. For example, a lot of the procedures for communicating with fixed wing aircraft are quite elaborate.
This open source US publication talks about some of the issues involved with aviation operations at sea. As does
this one. Given that a ship moves, flying operations and ship handling are things that place constraints on each other and need to be coordinated.
The whole ship aspects seem to be forgotten about far too often, but are key to safety. The current CVS/Harrier/STOVL skillset are just basics when compared to the CTOL skills needed in the future, but without lots of people with experience of the basics then transitioning to catapaults and arrestor gear (and aircraft that do not not stop before landing) can only be much more difficult. Aircraft will still need moving around on deck, the ship will still need to be on the right course/speed, to name to aspects, regardless of carrier type.
As I have said before:
I would suggest that basics are basics, regardless of whether the future is V/STOL or involves "Cats and traps". Will there be exchanges for lots of chockheads - moving live jets on deck 24 hours a day in all weather in rough sea states, the people who fuel, arm and work on aircraft on deck - amongst jet blast (and with FOD issues) the OOW and bridge team - who have to put the ship in the right place, direction and speed for aircraft to take off or land, Ops Room personnel - who have to operate sensors/weapons and talk to aircraft, maintainers of this equipment, landing aids maintainers, the ME watchkeepers keeping a nice level deck and increasing speed when needed, ATC types, Fighter Controllers, senior Officers in the carrier (Cdr(Air), Lt Cdr(Flying), Captain, XO) - they need to know how to run things, senior Officers elsewhere (MOD, Navy Command, task group commanders) who need to know how aircraft are used as task group weapons, etc?
Cats and traps are of course a different matter, and that expertise does not currently exist in the RN, and it cannot be practised without a carrier so equipped. But surely other skills do exist, and could (should) be retained with continued fixed wing embarkations?