Expansion - Not Likely
There are no circumstances I believe in which the armed forces will 'expand'.
The only times the RAF has 'expanded' since 1945 was briefly for Korea and then when the Thor & Bloodhound sqns were formed. The whole emphasis is to downsize, save money and unless the homeland is affected directly, that's how it's likely to continue.
The complexity is that size does not equate with capability but what seems to be overlooked is that you actually need a capability to project your capability.
The timescale for any future conflict is unlikely to allow for any expansion of capability. I also recall being on the margins of a conversation which went something like: 'we have to keep so many of aircraft X because if we don't, the Treasurer will never let us buy more of aircraft Y when we replace X'. This argument then became a numbers game not a capability game.
OH, my head hurts, it's too early to think about this ......... off to walk the dogs; it's perishing outside.
O-D