I do not think so. My libertarian hackles rise when I hear such a plan. There are plenty of filter programs parents or bluenoses can employ to protect them from content that they do not want to see. I’m only in favor of government action when that’s the best way, or the only way to solve a problem. In this case,it’s not the only way, or even the best way.
Further, if we did legislate a special domain for porn, who would decide those grey areas like sites dealing with self exams for breast cancer, safe sex, etc? Also, what legal authority would enforce it? The world police? The UN? If it were a US only action, all the porn sites would just move to friendlier soil. Finally, there are already tons of dot-com porn sites out there that have worked hard to build their page rank and reputation. It would not be fair to them to suddenly change the rules.
Very bad idea. Leave my dot-com porn alone. :-)