I'm not a tech type, but made illegal there will of course be ways around it- but it order for Bitcoin to be viable a LOT of people have to have those ways around it and have to be willing to commit a crime that may be made synonymous with child pornography, terrorism etc.
Personally if it were me running things I'd treat Bitcoin for what it is- new, and very good anti-counterfeiting tech. Make Bitcoins illegal, then make them obsolete by issuing dollar backed AmericaBits you could spend online or redeem at any bank. But getting way ahead of ourselves with that speculation...