Get the support. Repeal the amendment. Go full Lincoln: start implementing strict gun measures through statutes and EOs. Don't give a shit this time if conservatives get mad; if they threaten war, round them up and make examples out of them. And while the constitutionality battle winds its way through the courts, drag repeal toward the center of the Overton window until, like gay marriage, it becomes an obvious policy winner with overwhelming bipartisan support. Just in case, pack the court with liberal justices who will opine the RKBA back to a collective right which it was generally agreed to be until the far right took utter control of the NRA and the Republican Party.
Oh yeah, and sue, sue, sue. Sue gun manufacturers, ammo manufacturers, gun rights organizations, and politicians who voted and advocated against gun laws. The First Amendment only protects you from jail for your heinous speech; as we've seen with Alex Jones, it doesn't protect you from billion-dollar judgements if you choose to spread lies about the dangers of widespread gun availability, gun culture, and the violence these enable.
I believe it would be great if we could repeal the Second Amendment and replace it with something clearer and better suited to the 21st century. As it is, pretty much every discussion about guns ends with "The Second Amendment says no", and the conversation stops there.
As it stands, I think that the vagueness of the second amendment (due to the prefatory clause the gun-rights supporters claim means nothing at all) could have been used to have a coherent discussion. The Supreme Court agrees that the prefatory clause is irrelevant, and that's the end of it. There is no appeal from the Supreme Court except amendments, which might as well not exist.
So I don't think it's helpful to deflect that onto the fact that we can't talk about the Second Amendment. You know that it can't be changed, and between that and the Supreme Court, you've got absolute power to set the rules to whatever you want them to be. Everybody else is at your mercy, and so it's entirely on the "huge supporters of the Second Amendment" to listen to what people actually want -- not to get shot -- and find ways to bring that about.
The truth is that if you can't persuade me to give you what you want and the law is not on your side, then you don't get to have it. And that really is the end of it. That's what it means to live under the rule of law.
It's a good thing that repealing the 2A is nigh on impossible as far as I'm concerned. I don't see it as an obstacle. I see it as part of the bedrock of the American social contract.