In an ideal world, with unlimited resources, you'd keep the SHar, just in case.
But you wouldn't get much use out of it. In the post Cold War world, littoral ops against low air threat enemies have been the norm. By their nature such ops allow greater use of land based AD anyway. By their nature we tend to be operating with coalition partners who can provide AD better than we can with a few tired SHars.
Our carriers are too small to carry a viable mix of AD and OS fixed wing aircraft. If you take GR7s along, you can't carry enough SHars to do the AD job properly (to be able to sustain sufficient aircraft on CAP, etc.), and you don't have sufficient GRs either. So the sensible way to employ the carrier is to tailor its air wing to the requirement each time it sets sail, deploying SHars when you want to use the ship as fleet AD (albeit with a limited, basic OS/Recce capability) or deploying GRs when you want to project power or support deployed forces.
In today's world, you'll be deploying GR7s every time.
To pay to keep SHars (which are no longer routinely useful, and are merely a useful option to have 'up the sleeve') you'll have to get rid of something else. Unless the Admirals are happy to bin Trident (say) then you'll have to get rid of something which provides a capability which is actually useful, and which is regularly used.
The world has moved on, and there is no place to retain assets which don't pull their weight, and which are not regularly and routinely essential. Too many of those who argue the case for the SHar do so out of sentiment, out of narrow single-service dark blue prejudice or because they can't or won't recognise that the world has changed.
From a strictly single-service RN point of view, the SHar seems worth keeping because it might one day be useful, and it doesn't matter that (say) the Jaguar would have to be removed to pay for it, even though the Jaguar is regularly useful.
A truly bold policy would be to recognise that Fleet AD as a role can now be ceded to allies or land based assets and to drop it altogether. That's not what's happening, there'll merely be a short capability gap before JSF comes in.
Personally I'd go the whole hog and bin carrier aviation altogether, spending the money on decent SEAD, a proper replacement for the Canberra, two squadrons of surplus B-1s and loads of JAS 39s for the boys to fly!