I, for one, must be the only person out there that could care less about a FF nex. I like the idea, but not with the current e-mount. Yes, I know it's a technical possibility, but given the limitations of the optics, and given the weaknesses we've already seen with the NEX-7, I'm not sure that things translate well if you scale everything up to a FF sized sensor. If folks are grousing about corner softness on the NEX-7 can't WAIT to hear the complaints about the IQ of the NEX-9....
Yep, this is the big problem with putting a FF sensor in e-mount. Other FF mounts, like F mount and M mount, also have a smallish throat diameter like e-mount, but their registration distance is longer. The combination of both a smallish throat diameter and very short registration distance is a mechanical interference issue that can either be solved by:
A) Improving the sensors acceptance of light rays, like Leica, so that Sony can make FF NEX lenses that extend down into the throat more without edge issues. The VG-900 shows that Sony hasn't been interested in this, yet, as it seems to be smearing various M lenses quite a bit.
B) Making longer, more telecentric lenses, which are more or less similar in size to a-mount lenses with adapters.
As Lonnie says, there are already complaints about corner performance with the NEX-7 and some lenses, and Sony's aps-c lenses also get a lot of complaints in regards to how large they are. If Sony doesn't make big sensor improvements to accommodate this, I can't imagine how people will complain about the size of FF NEX lenses. The RX1 gets around this by being fixed lens, but making an interchangeable version will take some work.
p.s. I doubt Sony would put leaf shutters in every lens, but they certainly can work on making NEX shutters a little more quiet.