That makes my prediction that the Lions won’t tag Golladay tomorrow that much more convincing… 
I don’t think they can just move that deadline without NFLPA approval because It’s in the CBA.
I presume they’d just sign an Addendum to facilitate the 2021 salary cap calculation/determination.
They would have to but my point is they would need to get the NFLPA to agree to it. I’m not sure they would. I don’t see an advantage for them to do so.
Unless there is also a contractual provision which requires the two Parties to agree to the salary cap number for a particular year.
The cap number is a revenue share. It’s preset in the CBA as a percentage of the following years revenue.
Problem is that there was a major loss and if left as written in the CBA the cap would be around 160mil. This would have drastic implications on the league so the NFLPA and the NFL have agreed to spread out that loss over time and have set the cap minimum at 185 mil for this year.
The actual cap number hasn’t been set because they haven’t yet agreed too how they will actually spread it out.
So unless the NFLPA and NFL actually agree to extend the tag deadline it won’t get extended.
I do know there is a good faith clause in the CBA where both sides need to agree to work in good faith. So I assume the league could file a for a mediation if push came to shove and buy time that way I guess. I hadn’t thought of that until just now.
It will be interesting to see what happens.