Apple now says Feb.1 on their website. Local Best Buy took out their Mavic display case that had a "Coming soon" sign in it for a few months and not one to sell.
Apple local store told me mid-Nov. then mid-Dec. then mid-Jan. and now Feb. Who knows? Just say mid-Summer.
For now, they got some bugs to work out on their P4 Pro series in the meantime that grounds them post calibration. I wouldn't be surprised the Mavic has some issues too they want to address. No rush since the GoPro Karma competition disappeared either.