Hmmm.
I don't think that retiring SHar early and reducing or stopping the Typhoon buy are remotely comparable.
Retiring Shar leaves a short term gap in a small spectrum of capability (carrier-based fleet air defence). A replacement for SHar has already been selected. In the interim Fleet Air Defence can still be provided by other means (land based, allied, SAMs, etc.). We could decide that expeditionary ops involving carriers are something we'll no longer do (in the short or long term), and still be able to do expeditionary warfare (albeit with some restrictions).
From FOC in 2007 Typhoon will be a multi-role platform (even the Tranche 1 jets) replacing Jaguar and Tornado F3, and increasingly augmenting a dwindling GR4 fleet.
Even in the AD role it does more than the SHar, (UKAD, QRA, expeditionary AD/AS, maritime, etc.) and will do so more impressively (6+ BVRAAMs, HMS, longer endurance, longer missile reach, etc.) and so it would be quite possible to decide "the AD mission is less important, so we don't need SHar, but do still need Typhoon."
Carriers provide a capability that is needed infrequently, and one that can realistically and legitimately be provided by Allies, whereas the need for land based AD is 'constant' and therefore must be a national capability.