I share your concerns, but IMO it will never get to that point. For starters, the Supreme Court is charged with interpreting, and defending, the Constitution of the United States. Right now, it's likely a 5-4 court at worst on that issue. Odds are that President Trump will get to nominate at least one more Justice. We'll see how that plays out, but I just don't see a repeal of the 2nd Amendment.
And even the most liberal of the liberals realize that any "gun grab" would go over like a turd in the punch bowl, so I don't lose much sleep over that. But another version of the Brady Bill might be on the horizon. Of course, I have learned that you can never count on the government to do the right thing if another option is available, so we'll see.