Given the current state of the Senate, it seems unlikely there is going to be any big legislative changes before 2024. 2022 is still eons away (in political timescales) but a fairly likely scenario seems to be that the GOP will narrowly gain the House and the Democrats will pick up 1 seat in the Senate.
So we're largely arguing academic situations. And the thing about that is you then have a lot of people who are virtue signaling rather than genuinely arguing a position because they know their rhetorics, even their votes, won't change anything. It's why opposition parties always vote for campaign finance reform.
So I'm highly skeptical of the need for any government action here, be it sweeping legislation or antitrust. There are several reasons for this:
1. Big tech companies are more fragile than you might think. Government action is slow. As we've seen from Myspace, Yahoo and the like, big companies can disappear almost overnight. If a company can face an existential threat and possibly disappear within a few years then, by definition, it's not the monopoly you think it is. It's certainly not Standard Oil.
2. Western companies have been largely excluded from Chinese markets while those companies have far less restrictions elsewhere;
3. Chinese companies are essentially an extension of the state. US companies are not, not to the same degree anyway.
What we actually need is company-agnostic action that protects consumers, their data and what you can do that with that data. This is sort of happening already thanks to the EU (eg GDPR). The US needs to start extending those protections to US consumers. And that needs to apply to both domestic and foreign companies.