My understanding (please correct me if it's incorrect) is that the "worst-case" scenario for a broadcaster is that they may have to upload a record of political air time to a public file.

If an opposing candidate sees this, they can then request equal air time from that broadcaster.

The rule is in place so that one party or viewpoint can't dominate broadcast media. That's a good thing right?

The rule change here is that traditionally "bona fide" news programs have been, by default, issued an exception to the rule. That has spawned a bunch of "pseudo-news" shows that have also been claiming this exception. Here, the FCC is now saying "hey, you don't just automatically get granted an exception to the rule and get to call yourself a bona fide news program if you're not actually one"". That seems completely reasonable to me.

Broadcast media is held to this FCC standard because they are granted a monopoly for a broadcast spectrum, and it isn't physically possible for a competitor to broadcast on the same spectrum. Streaming etc... doesn't need to follow these rules.

I do think it's wrong that talk radio doesn't seem to be held to the same standard, though.

The worst case scenario now is not limited by process and law. Compliance with politics is taken into consideration for all government business. For examples, see the executive orders blacklisting specific law firms, the withholding of funds to states or areas that vote Democratic, and the threat of investigation into a network after a host said something the President didn't like.

Up until this month, talk show interviews were exempt from the equal time rule.