...the FCC regulates broadcast TV licenses NOT cable. The FCC can't do anything to force News Corp to divest itself of Fox News, Fox Sports, FX, or their other cable properties.
I guess some law could potentially pass in Congress that re-instituted broadcast ownership limits and required corporations that own broadcast stations to own a limited number of cable properties or newspapers. In the unlikely event of that happening, I'd speculate that corporations (including News Corp) would sell off their broadcast licenses for the stations they currently own, but continue to run their cable networks and provide network programming to broadcast affiliates - just as they are today. In other words, Fox would no longer have O&O stations - just supply programming to affiliates.