I think anyone who thinks we don't need infantry is clearly not thinking straight, but I haven't seen anyone suggest that here.
My original point was that determining how much fast air we need should not only depend on how big our land forces are... Except insofar as they all get paid for out of the same pot, which although important tends to impinge on reasoned argument. I think a lot of people would agree that our CAS capability should be sized to support what the land commanders need, as it is there to support them (the same applies for other primarily tactical assets in support of land forces such as SH, ASTOR etc).
But fast air because of its speed and reach (alongside UAVs for persistence) has a strategic role when we can't or don't wish to commit land forces. The use of Reaper in Pakistan is a current example and the use of Tornado and Jag between the 2 Gulf wars another. Given that Typhoon will end up doing CAS, AD, recce and all the non-CAS offensive roles, we shouldn't dismiss its importance. That's not to say that we need 200 of them, or that a carrier capability wouldn't be good, or that infantry isn't essential... Just that air can play a useful and (occasionally) decisive role not in direct support of land forces.