Having just laboured throught he whole thread (very few valid points and too much willy-waving) I'm surprised no-one mentioned what I would see as the biggest problem. (tongue only slightly in cheek).
Politicians are one group who know even less about air power than the average infantry officer. My biggest fear would be our cyclopian, non-driving Jockistani Chancellor ....
3 services = Defence Budget £ xM (where x=not enough).
Therefore 2 services = Defence Budget £ 0.67xM ....... (even more not enough!)
.... it's about as detailed as defence thinking gets in the Treasury ......