they've never done live feeds of any of the panels - this year they announced they will have one for the video game panel but that is it
And at the big panels (including parks and resorts) they make people put their cell phones in protective cases so they can't stream it
Personally I wish they would - not everyone can make it to CA (even if just for D23 Gold Members) or it would be cool if they did it as like closed-circuit to event halls in major cities and have like mini-D23 satellite locations for fans to gather and watch the panels together