The delay is VZW's doing, they want battery life and LTE connectivity beyond perfect. I'm not sure what you mean by revision changes, but here's what I took from the training:
1. Simultaneous voice and data will be LTE/CDMA based.. They knew about the capability of this happening over 3G but it may not be the case anymore.
Its actually technically going over EVDO Rev. A, as BMX has reported. There's a standard called VoRA, which uses pre-existing EVDO Rev A networks and allows for simultaneous voice and data. Its nowhere near as smooth as what it would be if its based on LTE/CDMA, but its still coming.