Scalia did not say that all bans were unconstitutional, but from his decision (and I haven’t read it for awhile) it would seem that the ban would have to at least pass the rational basis test (which an assault weapon ban can not pass) - or possibly would have to pass the test of there being no rational reason for ownership of the weapon -(this is based on Scalia’s justification for why US v. Miller still stands).
He also said that they can’t ban M16s because that would sever the 2ndA’s preamble. ...so, let’s push a case to end the ban on M16s!