Correct me if I'm wrong, but these rulings would only hold power in the EU though, no? That's great for the EU, but that means we've still got to fix the problem everywhere else.
Yes, but it'll affect the whole market. The EU is a wealthy market with 510 million consumers - if Google's stranglehold on Android is broken there, then it is profoundly undermined internationally. Google might continue with anti-competitive practices outside the EU, but non-EU citizens will be free to import a device that is compliant with the EU ruling. In many cases, it will be possible to install an EU-compliant ROM on devices bought elsewhere. Some non-EU countries may decide to follow the lead of the European Commission and pass similar antitrust rulings.
Given the EU doesn’t affect the rest of the world like they think they do (see GDPR) and also given that I can already install a ROM on just about any Android phone, nothing will change for the rest of us.
As long as it's more expensive for these companies to maintain 2 frameworks then it will be beneficial for everyone. This of course might not be the case.