THE FIX I FOUND IS THIS...
As annoying as this is, I think the best way I found when Premiere was caught in some Force Quit hang was to:

Open Activity Monitor
Select "WindowServer"
Hit the Stop (stop sign) button in the upper left of the Activity Monitor window
It will warn you that it will log you out if you kill this activity... DO IT ANYWAY
Your login screen should come up in a second...
Log back in and the Premiere app should NOT appear in your Force Quit window anymore, meaning it's closed.

My theory is this is less damaging to your system drive than doing a hard restart, but I leave it to the engineers to comment on that.

Same problem on my maxed out MacBook Pro 16" is this still not fixed?

Same. Brand new 16 inch MBP Radeon 48 8gb 32 Gb Ram and can't restart my mac because Premiere won't force quit.

Same here. Premiere crashed, I can't re-open or restart my computer without a forced shut down.

Having the same issue on my new (maxed out) MacBook Pro 16". Not even sure how to force shut down this computer without a physical power button. Seems to be related to the program trying to open content from my work's OneDrive (Microsoft) cloud storage that isn't already downloaded on my computer.

Similar problem, but with After Effects. Once it crashes you cannot open it again without a full forced shutdown of the whole computer

Same here on a 2016 MacBook Pro...

I'm getting the exact same problem on the new i9 8-core 2019 iMac 5K w/ Vega 48.

This **** is unbelievable. No wonder everyone is going to Davinci Resolve.

Same happens to me on new Imac 2019. 3.6ghz, Radeon 48 8gb, 64gb RAM, Running 2018 PPro.