I doubt it, they would likely use a different earcup design, while what we've seen so far looks more like a modified version of the HD800's design.https://patents.google.com/patent/D...l&assignee=sennheiser&after=priority:20160101
At least they have patent for planars. It's unsure will Senn use this planar patent in the HD820, judging it's pretty recent one (2016/05) they might...(?)
Credit to @iDesign from "other forum" for finding this.
If they go planar, I'd expect it to be a different series (HD900).