Like, how often is there a viewer who actively watches both/switches between the two?
It's very polarizing.
I can't think of any way to fix it culturally. One party thinks the other is deranged and lying.
Will it get worse? Will it get better? Where does this lead us?
Yes cnn is a newsertainement org like fox, but it’s not the anti-fox. For starters, No one actually cares about cnn except fox watchers.
In the U.S., we didn't make war with eachother, but we hardly "mended" our political misaligmnets from the 1920s and 30s either. In the post war years we simply made talking about communism in the media illegal, blacklisted progressive voices, and ran witchhunts under mccarthyism to root it out of office. Then after mccarthyism, we used the civil rights era and drugs to further alienate political groups from what is legal, proper, and ordained as bonafide american by the ruling class, versus unifying many of these new progressive ideas into our national culture. In later years we divided the labor class into irreconcilable factions, neither of which often thinks critically of the facts of their situation but rather believes the words of their chosen political party leaders as gospel, and never looking back or forward either unless told by said leaders.
If we consider history and our current status, we are at the moment where divisions are being made, and once divided into a group people don't tend to switch groups, they usually die believing that ideology they latch themselves on to. What is next is probably either two things: a period of instability as different groups vie for power (unlikely as the ruling class is unified in its position in the class war above all, and much political commentary is just fodder to distract from the class war), or, radicals will get the hippy treatment, and be pacified by both the conveniences of modern American capitalistic life, as well as the fact that their radical ideology receives no honest voice at all in mass media or wider politics.