I think you are a little too optimistic when you say "if unincorporated, the feds must lay off and leave it to the states." You know that the feds will still try and get their gun control legislation to pass strict scrutiny. Heck, the First Amendment sure didn't stop the feds from passing CFR.
The second amendment is not incorporated. Any federal law passed under the second amendment applies only to the federal government, not the states. This was true with all other previously unincorporated amendments.
Assuming they were passed under an incorporated second amendment, do you think the 1968 GCA and the 1994 AWB needed to pass strict scrutiny? I don't. I think the USSC would rule that these two statutes merely had an incidental effect on the rights protected by the second amendment.