Please clarify what 'fully EF compatible new mount' means to you:
- If you mean what everyone else is doing -- thin flange distance plus EF adaptor -- then yes. 100% they need a few new lenses a launch. Hopefully they are lenses that make the size savings pop and are not clones of higher end EF glass (which would send EF users into a panic that EF is going away, even with an adaptor in the mix).
- If you mean it's straight up identical physically to EF but it secretly has fancy/improved lens communications, I'd wonder why they did it, have a jillion questions about how this isn't fragmentation of the mount for future lenses a la Nikon. Yes, they could put out a new EF-Fancy 24-70 f/2.8 Special AF to show this off, but I'd just be scratching my head why they did.
- If you mean weird new mount that receives two different kinds of lenses, like the EF-X concept or a variable/actuated flange distance, then yes, some nestled/tucked-in lenses would be in order.
But if it's just straight EF, I would argue no new lenses need to be made: kit the damn thing with the 24-105L II or something. In fact, it might be best
not to put out new glass at launch. There's no better way to hammer home that EF will be money on this new system than to kit EF with it and show how perfectly it works.
- A