Something that should be addressed as soon as possible is reducing the capacity of foreign actors to influence politics through organized trolling.
There has been a lot of gaslighting around this issue, but the fact is that the United States has been protected by two vast oceans for its entire history, but it opened a conduit into its heartland for foreign mischief-makers through Facebook and Twitter. Whether it helped Trump or not in 2016 (frankly, I think it probably did but it's exhausting to debate this so I won't) it does represent a gaping hole in America's defenses.
Until this election, there seemed to be a clear pattern (in the English speaking world anyway) that allowed one to reliably predict the winner of an election by seeing which side the trolls supported.
There are no First Amendment protections for Russian/Iranian/Macedonian click or troll farms. Detecting VPNs and other attempts to conceal traffic is not an insurmountable technical challenge, yet it isn't done consistently.
The seductive "Arab Spring" approach to letting free speech run rampant on social media turned out to be a mirage. Not only was the Arab Spring reversed in Egypt, based on my discussions with Egyptians, Facebook was turned into a tool of repression after the counter-revolution took hold.
(Yes, the irony of posting this from a throwaway account doesn't escape me, but there's a difference between clearly anonymous speech, and speech that misrepresents its source).