In a post Heller world, I don't think that an assault weapons ban would survive a supreme court challenge. In my opinion anyway.
The Heller ruling pretty much gutted US v Miller 1934 on the grounds that the plaintiff never filed a brief with the court or appeared for oral arguments, and should therefor be carefully scrutinized before being used as precedent. Heller stated this, and reduced the scope of Miller to only that of excluding certain types firearms from 2A protections - those that are commonly used by criminals in crime, and not commonly used by law abiding citizens for lawful purposes. The "assault weapon" doesn't fit this category, as there are hundreds of thousands owned by law abiding citizens for lawful purposes.
In other words, Heller established that almost all firearms are protected under 2A. They can play with registration schemes and such things, increase the difficulty of ownership, etc. but an outright ban like the one in 1994 would likely be struck down by the current court. I'm sure that Feinstein and friends are well aware of this, which is why they are discussing the possibility of changing "assault weapons" to be title II weapons.
In my amateur non-lawyer opinion, there are two ways that they could try to reclassify "assault weapons" as title II - by explicitly passing new legislation, or implicitly by executive order that "assault weapons" have always actually been Any Other Weapons, and that they are only now realized this. I have no idea if this would survive a court challenge, the AOW definition of the NFA was intentionally written vaguely, so it might. I would hope not though, and the fact that there are so many in existence currently as a title I firearm tends to make me think that a court would find that kind of change to be overreaching without the legislatures involvement. At least a reasonable court that restricts itself to simply deciding issues of existing law.
Honestly, I think the best we can hope for is for the libs overestimate their "mandate"to enact new gun control after CT and overreach and get shut down hard.