I've been thinking about this since edster's OP. I won't get into my personal "line in the sand" here, but when he first posted, I thought that we weren't that close. Since then, which was only 10 days ago, I believe things have gotten closer and I believe it will get much worse. To that end, I've been thinking about individual lines in the sand and collective or society's line in the sand and what it will take to bring about change. Right now, there seems to be a lot individual lines in the sand and occasionally groups will make their line known and make their stand. Be it with regard to ranching issues, racial stuff, gun rights/control, etc.
With regards to line in the sand with regards to gun control, I envision that there won't be sufficient numbers who have reached their "line in the sand" and band together to effect change until after 2A has been eroded to the point of confiscation and beyond. I hope it never gets there, but that's what I envision (and hope I am wrong). I just see the tide is where too many people are brainwashed into guns=bad, no guns=security. Of course the members of this board wouldn't be in that category.
I view this issue as evolving like a pendulum. We haven't reached the bottom of the pendulum swing and the pendulum will need to swing to the "other side" before making it's way back to "our side". That it will take the pendulum swing to get to the "other side" far enough to get those brainwashed people to wake up and see the light.
Not sure if that answers the question that was asked, but those are my thoughts. . .