DC v. Heller was wrong. Go read the context around all of the places where a militia is mentioned in the constitution. It’s a pretty clear difference from the world that DC v. Heller created.
Yea, there's a lot of history around types of militias, too (especially formal v. informal militias). The historical arguments were what got me on this: the 'prefatory' clause is pretty clearly there to point out that formal militias are allowed, and make no mention of informal militias.
The Constitution is a little ambiguous as to whether or not a citizen must join a militia in order to keep a gun at home.
...however in the absence of militias in the US today, it makes sense that even if that requirement was initially envisioned (which is very debatable), it's no longer reasonable.
It's historically interesting to note that different versions of the amendment were ratified, both including and not including that last comma.