I hope that Verizon rep gets fired. Certain LTE chips allow simultaneous voice and data. It doesn't do everything very well yet, but it's getting there.
As for speculation, the next iPhone should be LTE equipped for both Verizon and AT&T. I say should in the sense that I think it should on principal. We all know principal theory and reality don't mix well with Apple. Apple will always do what's safe. They'll do what they know will work. If you want phones that push the latest and greatest, regardless of whether or not it's ready for mainstream users, go Android.
I think they'll wait for that better LTE chip. I can't think of the name. It should be available by the time the next iPhone is ready, and they can test it and ensure it's going to work with at least the same if not better battery life.
If all these stars don't line up, just prepare for another 3G iPhone.