I’ve actually expected that the December 8 deadline will push, but not until we get close, because if major airlines are far off from compliance the Biden administration won’t want to be blamed for ruining holiday travel due to mass cancellations.
They’ll need a reason for the delay, of course, that isn’t this. They will want to declare victory, or offer an extension on technical grounds. This will be especially tough to avoid if Covid-19 prevalence in the U.S. is low overall as the end of November approaches.