It's hard to cancel popular shows for political reasons (at least in america) - it's too transparent.

But its possible to starve them of talent, funding and eventually let them wither into obscurity, by not promoting nor giving it the opportunity to flourish.

But there's still youtube even if these incumbent media outlets are compromised - independents can still create and distribute there. This is very different from the airwaves or cable.

Didn't the South Park contract predate the Skydance takeover?

Yes but Paramount was already debating whether to bribe Trump and clamping down on news shows that reported anything critical of Trump.