Ha! Let 'em try. The main reason the (un)Fairness Doctrine was scrapped in the first place was because the SCOTUS gave a none-too-subtle hint to the FCC that the state of brodacast communication was about to reach a point where the FD would no longer be constitutionally viable ... and they said this in 1984! Since then, the number of cable channels has gone up by a couple of orders of magnitude, three more broadcast networks have come into existence, the number of actual TV and radio stations has exploded, and then, of course, came the Internet.
The FR made some sense when it was instituted in 1949, and there was practically nothing around but the three networks. It would serve absolutely no purpose today but to supress popular speech (and destroy much of the broadcast industry in the process, because they would be disallowed from running shows that actually got ratings). If it were ever reinstituted by the FCC, or forced into law by the RATS, an immediate injunction would be issued, and the SCOTUS would eventually rip it to shreds. And the chances of such a law ever getting passed is almost zero in the first place, since the National Association of Broadcasters is generally considered the most powerful lobby in Washington by far, and they of course HATE the FD.