Nope, if you are in Canada for example they'll just take your assets. They strongarmed the Canadian banks into forcing disclosure of all US citizens bank account contents.

And there are plenty of people around the world who have discovered they have US citizenship without knowing it before. And now they have to file with the IRS.

Glad I never got dual citizenship through my grandmother. In the past having USian citizenship would be nice. Now it would just be a pain.