They never applied to the Internet, cable TV, or cell phone bandwidth. And those have become the dominant forms of communication. Only around 15% of people get over-the-air TV. And while the numbers for radio are somewhat higher, it's competing against much more targeted messaging on social media and web advertising -- both of which are unregulated.
So even if you reinstated airtime laws, and actually enforced them, I don't think it would make much difference. It's not the loss of equal time that allows obviously-biased mass media TV "news" channels to exist, but the fact that they're not broadcast over the air.
Amending the laws to cover those would almost certainly run you afoul of the first amendment, since the equal time doctrines were only legal because the bandwidth was so restricted. The unrestricted bandwidth of the Internet will make it much harder to justify.
Bear in mind, it's not like we have no control over debate platforms now - the rule enforcement has been lacking but foreign money in campaigns is strictly verbotten, free speech has some limits.
1. Name recognition, if nobody knows who you are nobody will vote for you - this can be countered (or effectively reduced) by just super charging public information sources on all candidates, and some of the equal airtime laws (repealed under clinton urgh) helped with this issue.
2. Policy clarity, reduction of misinformation allowing publicly funded debates for candidates to self-advocate for positions and making sure the media is subsidized for covering those debates and fact checking helps inform the public.
If we move over to public funded elections, reinstate equal airtime and subsidize national debates we'll be in a good place - then arm the FEC and let them come down on a hammer on anyone trying to skirt the rules by trying to utilize either their own or their friends assets to give that person a bump. I think there is an assumption in the US that telephoning for a candidate is a valid and natural donation of time and support, and we need to break that because telephoning is already well onto the slippery slope. Lastly, Canada has an advantage here that the season is intensely short for campaigning, so it limits how much shady stuff you can actually pull off.