IMO there are two ways forward here.
1. Build a single large 40,000t LHD to replace the Albions. Add a 12x F35 capability to enable a LHA role and rotate with the 2x CVFs ensuring permanent F35 availability. Clearly the current setup can’t deliver that and when QE goes into deep refit it’s just going to become more obvious. Carry on with 4x MRSS as planned.
2. Build 2x Juan Carlos LHD virtually unaltered (similar principle as T31) with the Navantia/BMT/H&W consortium to replace the Albions. Add F35 capability to the LHDs. Operate 1x CVF and 1x LHD as LHA at high readiness with second hulls minimally crewed. Rotate every 4-6 months. Replace current amphibs and auxiliaries with similar vessels. The 3x Bays replaced by 3 new Enforcers and construct 2x BMT AEGIR platform joint support vessels with maximised hospital facilities to replace Argus and the Waves. IMO this is the best way for RN to retain both CVFs over the longer term. The construction costs will be high but the operating costs will be manageable over the longer term.
Apart from securing the carriers Option 2 also gives RN the ability to upscale very rapidly to 2x CSGs and 2x independent ARGs if the security landscape ever deteriorated to the extent that it was required. A huge strategic plus for the U.K. and NATO.
Perhaps Option 1 is very crudely the 2.5% GDP version and Option 2 is the 3% GDP version. Regardless, unless a continued policy of managed decline is preferable then something along these lines is worthy of consideration IMO.