The only aspect of managed IPTV that I could foresee AT&T still using on this new service would be some form of multicast for linear channels served to customers who are connected to the internet via AT&T. Everything else (cloud DVR and video on-demand) will be OTT unicast streams. And even if they do end up doing multicast for linear channels to their own broadband customers, it would probably somehow be integrated into their new streaming video platform. I doubt that they would continue to use any of the current Uverse TV IPTV platform, which is based on
Ericsson Mediaroom. (So forget about those existing Uverse TV servers.)
Some time ago, AT&T acquired
Quickplay, a move which I'm sure fueled the development of their own new cloud-based OTT streaming platform. AT&T no longer has a need to license solutions from outside providers like Ericsson since they now have their own in-house platform. I would imagine that Quickplay brought them the tools they would need to provision multicast video. Quickplay's website specifically points out that they support LTE-Broadcast, which is a form of multicast video specialized for distribution via cellular 4G LTE networks. Perhaps we'll see AT&T deploy multicast streams of the most popular live linear channels not only to their home broadband customers but also via LTE-Broadcast to their AT&T Wireless customers who use their video apps (DirecTV, DirecTV Now, etc.).