Counting on the SCOTUS to save us and indeed rule out all this bullshit and restore the Constitution is like counting on your defense to force a turnover when the other team is on the two yard line with four downs to play, and then return the turnover for a touchdown.
I don't even want to speculate on how the court will rule under its current composition. I really find it unlikely that Justice Scalia is going to step forth and start passing out PMAGs and SAWs because they are the most appropriate weapons for militia usage. We do know that almost every appeals court has upheld nearly every regulation/infringement under at least intermediate scrutiny with the exception of Maryland and Illinois CCW.
If one of the Heller 5 gets replaced by Pres Obama I feel confident in saying that even the framework in Heller (2A is an individual right that protects weapons in common use) is subject to being thrown out entirely, and the 2A eviscerated. The Dissent in McDonald said:
"In sum, the Framers did not write the Second Amendment in order to protect a private right of armed self defense. There has been, and is, no consensus that the right is, or was, 'fundamental.'"
The libs have nothing to lose by overreaching. They can either negotiate down, or if they get lucky and it all passes, they can see what SCOTUS does. If SCOTUS throws it out or waters it down they then just try another way to subvert the Constitution. It isn't like they'll go to jail, be personally liable/sued, or get thrown out of office for pushing something that turns out to be unconstitutional. In fact they'll likely be able to get PR value out of it, "send me back to office to fight the evil conservative justices! Only I will stand in the face of dangerous judges who oppose common sense safety regulations!"