Block it by a paywall. But they wouldn't do that because they would stop showing up in search engines. Google is providing a free service by directing traffic to these companies.
Reminds me of the LinkedIn case about bots crawling their website.
We've been through this in Germany. Publishers demanded to be paid for Google usage of results and news snippets. Google thankfully didn't give in to such a ridiculous demand and gave publishers the option to de-index them or keep listing them for free. Obviously all of them opted for the latter.
For google this will be a pure economics game, and when they passed the other laws Google looked at the numbers and noped out.
The same will be true for Australia.
I do not see the UK, US, or any of the emerging economies pulling this, so the EU and Australia will alone in this battle and the amount of money being demanded it seems to me most likely exceeds google profit, so they will just end the service to the nations, and blacklist the sites from search
Search will be fine because 3rd party sites will be indexed so it will be a 2 hope, and given the incestuous nature of "news" today where every story is written more or less than same on 100+ sites all over the globe I am sure people will find the news they are looking for just fine with out those sites in the index
The Eu and Australia are massively overplaying their hand
They can unite and tantrum all they want but it won't change the underlying reality any more than fervent demands for a "good people only" backdoor encryption won't exist.