Absolutely, speaking as someone who built an exchange and spent a lot of time trying to figure out a legal route to operate it (I coded, my co-founder was a lawyer).
That strategy didn't work for Liberty Reserve, which was in Costa Rica. If Uncle Sam doesn't like what you're doing, he'll find you wherever you are and get you somehow.
Not if you want to ever set foot in the US again. If the SEC/CFTC really wants to nab you, they will. There's almost no way to prevent Americans from using your service and once they do you are wide open to any prosecutor worth their salt.
Woe to they who attempt to do so without counsel.