If anyone's interested, I found the discussion about all the projects that were going on around the time the clip with Tommy Lee was first posted. (Funny how time flies. In my head I was thinking it was 2 or 3 years ago; but it was actually just one year ago, almost to the day.)
It started here with post #815:
https://drycounty.com/jovitalk/bon-j...91/page82.html
After all the speculating and theorizing it kinda fades after Yovana's post (#851) about Parker's album and the "Who Ya Gonna Call" doc that he was working on with Strine. As I said, there were no conclusions drawn; just a bunch of guesses.
ETA: I just posted a link on the 2020 album thread about Motley Crue and Def Lepoard still planning to go forward with their stadium tour this summer. The article also mentioned that Tommy Lee's "working on a new solo album." I assume it's the same album that he was working on (which was supposedly being released in "the next 3-4 weeks") when the clip of him and Richie in the studio was filmed.