First off, as far as whether AA batteries could power an MT-G2, it really all comes down to numbers. Given enough AA batteries, you could literally light a city. So yes, you could build an MT-G2 powered light using AA batteries. In fact, if you ran a 6s3p arrangement, you could run an MT-G2 at full power for about two hours on common Eneloops (longer with Eneloop XXs or Duracell Ion Cores). This light would probably be about the size of a 5D Mag. But smaller lights could be made if less runtime is needed.
As far as anyone making such a light, I have not heard anything other than a vague rumor that Nitecore might be considering it. But that doesn't mean much. On the other hand, you could always build your own. One way would be to use a 2D Mag and run six AA batteries in two 3AA series holders (or 6 AA batteries in one series holder, if you can get one). You could run 24xAA on a 5D Mag. Or you could also run 18 AA batteries in six 3xAA parallel adaptors in a 6D Mag (or maybe that 6D light they sell at Autozone). Of course, at this point, you're probably better off running the light on D batteries.