At the trial court, we're just at the motion to dismiss. Some justices may prefer to nail down the factual basis before granting cert.
But one or more justices may be thinking less categorically—i.e., you cannot sue under state consumer protection laws, except in X, Y, Z circumstance.
(Note: SCOTUS does not give reasoning for why it declined to take up a case, so this is pure conjecture.)
The only surviving cause of action is an unlawful marketing claim. Plaintiffs are arguing that Remington Arms purposefully marketed the AR-15 for unlawful use. That's what the trial will be about.
The issue here will be what the facts show, and it's going to be a heavy lift
Yes, this sounds preposterous. That's what they're going to ask a jury to believe, however.