What's a critical mass? You sell subscriptions and hire journalists in proportion to how many people subscribe.

The "critical mass" to hire the first journalist is like 1000 people.

Huge publications like that only exist because of the historical capital cost of a printing press. Using traditional numbers, e.g. a city of 500k people 10% of whom subscribe to the local outlet, you can fund ~50 full-time local journalists. Which is the same whether they all work for one publication or they all work for themselves.

"Publications" will probably become subscription aggregators. So instead of 50,000 people each paying $10/month to one of 50 independent journalists such that they each have 1000 subscribers, all 50,000 people pay $10/month to the aggregator and then get access to the work of all 50 journalists.

So how easy do you think it is for one journalist to produce content that 1000 people will pay $100/year for? (And that number is probably too low because you probably have significant marketing expenses if nothing else.)

I mean, there are a lot of people already doing it on Substack.

The common marketing mechanism seems to be to make many of the articles available to non-subscribers (or do this after a time delay), and then they get spread around on social media which acts as promotion for the author.

I wouldn't be surprised if there are some substack newsletters that make that kind of money, especially if people brought a large audience from elsewhere. I doubt many of them are covering local news which is what this sub-thread was about. Personally, I doubt I'd pay $100/year for a newsletter unless it were making me money or really delved into some niche topic of significant interest not well-covered elsewhere. But I'm glad if some people are making a living off it.