Personally, i have no interest in a midi controller with a built in audio interface. IMO, there isn't a need for a new controller, as there is a lot more utilisation that could be added to the old controller.
I'm just hoping that with the launch of a new controller, they add a whole bunch of new functionality, which will also be available with the old version of Push. Full access to Lives browser for a start (third party plugins, templates, projects and tracks, audio files etc etc) and some sort of meaningful functionality when in arrangement mode too would be welcomed.