The legislators who have been waiting have been there for a long time. Lautenberg, McCarthy, and Feinstein know that this is their last shot. That doesn't mean it's a GOOD shot. They are in the position where they have a lame-duck congress that would love to talk about ANYTHING but the budget, and a crisis which is slightly worse than previous crises. This is as close as they are going to get before they retire. They are too old to ride out the publicity cycle anymore. This is why Feinstein upped the ante and threw on a lot of stuff in addition to the bill which has already been ignored more than a dozen times. When they retire in the next election or two, who will be the senators and congresspeople who trot these bills out every session? They have been alone for a long time.
The ban passed in 1994 by two votes, with sneaky process, a sunset clause, and a democratic majority. Bill Clinton stated that it was the single-biggest factor that cost him both houses. When Obama took office in 2009, sixty some-odd Democrat congressmen, knowing full-well the intentions of Holder and Obama, sent them a letter telling them not to bother with any new gun laws, because they won't vote for them. Most of them are still in office. In 1994, we as a gun community were poorly organized and not media savvy at all. Very few people owned AR-pattern rifles, as compared to today. In the majority opinion for the Heller decision, it was stated that guns that are 'in common use' are protected. Any new ban would be working against that language. Stare Decisis directs that unless there is any new evidence, the existing ruling will stand. (However, this would be one of those times you would regret it if Obama had a chance to fill those court seats first.)
So if Feinstein gets (by my count) three lawmakers to flip, no, I'm not calling it a done deal. It is safe to flip when the law has a very small chance of making it to the floor at all. She's yelling louder, but it's the same thing she has been yelling for decades. The fervor was at its peak about a week ago. They will not get stronger. People will not get MORE intense about this.