Definitely BT Sport channels 1-3 & ESPN. I'm assuming they'll be HD, or at least have HD as an option. I don't know if the Extra channels will be available but for NowTV to have full access to the Champions League games they would have to be made available.
Although if I am not mistaken I believe HDR is now available.
Do you happen to have a link for a source or was it over the phone with their customer service reps?
As much as I want to believe you, just the lack of official word from BT or Sky makes me think it wont be happening in July. Hopefully I am proven completely wrong though.