There is a lot of theoretical goodies coming from Sony. But I'm waiting until all the hands on reviews come about before I even look at these new cameras. The A7 series is nice but not enough to make me buy one. The A7II and the A9 hold promise but it's hard for me to leave my a99 for one. I've been saying this for years but lens support for the E/FE mount is just awful. Sony can't even make an f/1.4 lens for it. if you want an f/1.4 you'll need a fully manual lens that was not intended for the e mount. Sure you can get Rokinon/Samyang in e mounts but the lenses are so large that they are borderline ridiculous on a small a7. My Rokinon 35mm f/1.4 is a wonderful lens. I love using it. But even on my a99 it is a large lens. On my a6000 its comical. The a9 sounds fine and good but it's hard to leave the dead A mount for the barely living e mount. I also find it concerning that third party brands won't make e mount lenses either.
The 3rd parties don't make lenses for it, because of how different it is. Ultimately, Canon, Nikon, and a-mount lenses are very very similar -- only take slight changes in the production line for each version. E-mount would require a completely different design. I think this is also one of the reasons Sony is concentrating on e-mount and offering cheap e-mount bodies -- because they can then lock you into Sony lenses. You can buy the a99 and then build a complete kit without ever buying a Sony lens. Not true with e-mount.
Anyway, according to their roadmap, they will have 20+ full frame e-mount lenses by the end of next year. That would equal a-mount. Plus, ibis does make it much more appealing to use a-mount lenses with adapter.
But nobody can change physics. 1.4 aperture lenses will always be large. 2.8 zoom lenses will always be large. So yeah, to many of us, e-mount cameras will always feel too small, but that's a selling point to others.
Ironically, by changing the a-mount from dSLR to dSLT, they have created less reason for its continued existence. If Canon or Nikon were to truly develop a full mirrorless line, many people would still want the traditional cameras for the OVF, far better battery life, etc. But obviously the a99 doesn't have ovf. It's battery is only slightly less pathetic than the a7.
It has gotten to the point where the only real differences between the a99 and the a7ii:
A99 is slightly bigger, 2 memory card slots, and slightly less pathetic battery.
A7ii -- better image quality, smaller, cheaper, wifi, and better stabilization.
As a long time a-mount user who still cares about the system, I hope they do release a truly advanced a99ii... But I feel even once they do, it will offer few competitive advantages over the a9. And without competitive advantages, there will never be an a99iii.