I would have thought (hoped???) that any major changes like scrapping / significantly re-structuring of the AFPS would be done in a similar way to the implementation of AFPS 05 i.e. if you're already in and serving on that scheme at a specific date, then you retain the benefit, but all personnel joining after that date go on to a new scheme. And what if you're already drawing your pension.
However, as Spheroid rightly states, this will be the final nail in the coffin for the Forces. As it stands, there are many experienced personnel, officers and NCOs who are effectively kept in by the 'pension trap'. Whilst not ideal to have your personnel motivated purely by money, you cannot get around the fact that it means a significant level of experience is retained. If you then open the trap door, you give people no incentive at all to stay and you can then watch your key personnel walking.
This is going to be a minefield, and ultimately, a real indication of the government's (either side) alleged commitment to the forces.