This is why you don't give into baseless threats.
We knew this would happen.
There are several democratic senators who are not that stupid.
From the article:
As I’ve written before, even if Democrats have a wave election and manage to garner a 51 or 52 seat majority in the Senate, the idea that they would have the votes to court pack has always been suspect. Joe Manchin would be expected to be a hard no, and he’s confirmed that now. Diane Feinstein has also said she wouldn’t support a move despite her fairly liberal demeanor as a Senator from California. Overall, pretty much any red-state Democrat would be very tempted to not go that direction as it would jeopardize their re-election chances.
So, no court packing.
Now what ?