I agree that Graham and DeWine can't be legally held to this agreement and they might agree to go nuclear if the filibuster is abused. However, they did NOT put this option in the agreement! If they do go back on it then charges of bad faith by the 'Rats would have some merit, which I would hate.
And they'd be right!
They won't be able to hide their position behind platitudes or some "make peace" agreement quite as easily the next time around.
I'm not sure the Constitutional option has a chance in this Senate's makeup. But the fact that these 14 put up a public show is going to bring some heat on them. They may feel different the next time the issue is presented, which might be as soon as a month from now, and is darn near certain to be in the next 18 months. And if these Senators can't abide by the Constitution, it might affect them in an election campaign.
I see the situation as about as uncertain now as it was 10 hours ago - except now we have new knowledge, some unexpected names.