If they have shown the ability to control speech on their platforms section 230 should be repealed and Google etc should be responsible for the content on their property like any other publisher.

The first instance is property rights. The second is copyright, a privilege granted by the government at the expense of others' property rights. When a private party leverages copyright to conduct censorship it's ultimately the government that is responsible for violating the victim's freedom of speech. Google certainly has the right to grant or deny access to their services as they please, but that is not the same as having a natural right to decide how the software they develop is used after it has already been released to the public.

I think that’s precisely what’s starting to be discussed now at national levels, with investigations into Apple, Facebook and Google in the EU and the USA.

In many countries, utilities are commercial entities, but they can’t refuse to serve customers because of what they say. I can see a future where we think the same of the big players on the web: commercial, but still public utilities.

Problem of course is that many countries also fear a completely open internet. Providers already have to filter pornography, hate speech, etc. So, would we end up with commercial entities that cannot filter the content published on their platform to suit their norms, but must filter it to suit the norms of the government? If so, would that apply to all sites, including, say, Hacker News, or pro- or anti-abortus sites, or just to large ones? If so, what’s ‘large’?