With the way things are progressing, I believe there is a good chance we'll see hardened checkpoints on the interstates by the end of this decade.
All it would take is a terrorist attack involving vehicles, or a 'war on tobaco' as you mention, or a 'war on guns' along the lines of Travis McGee's book.
Having said that, hardened checkpoints on the interstates will likely constitute "the line" for many Patriots.
I just hope there are enough.
I have some doubts, but then again that could be because I live amongst the Jersey sheeple, they have been well programed.