Are opium or DDT Constitutionally protected rights? There is a higher bar involved here.
No, no rights are absolute. However, that does not mean that rights can be changed on a whim, ignoring all previous rulings or precedent.
Semi-automatic is a very low bar to try to set. I don't think it would work without a new amendment.
I contend that the semi-automatic firing system fed by a high capacity magazine is not a constitutionally protected right. And citing that position is not taken on a whim. It is cited on the bullet riddled corpses of innocent Americans. If other weapons can be banned due to their unnecessary lethality, assault weapons can be too.
Is your definition of assault weapons semi-automatic weapons? That's......ridiculous, really. There are all sorts of semi-automatic weapons. Also, assault weapons is often a pretty vague term.
Magazine capacity is a somewhat different issue.
Let us then define "assault weapon".
My definition would include, but not be limited by these attributes; a weapon using a semi or fully automatic firing system and can be fed by a magazine containing ten or more rounds. A weapon whose rounds are fired in a tumbling trajectory rather than a smooth spiral trajectory.
It's the rate of fire that puts the 'mass' in 'mass shooting'. Revolvers containing six or fewer rounds, bolt action rifles and pump action shotguns containing eight or fewer rounds would be acceptable as these weapons are designed for self defense or sport.
My great fear is that the debate will be bogged down by cosmetics as the previous assault weapon ban debate was. Grips, stocks, flash suppressors have nothing to do with the essential problem of rate of fire.