All the major newspapers (e.g., WSJ) and magazines (e.g., NatGeo) of the world have already transitioned to online subscription model.

Guess whether their reader base has increased or decreased from their heydays.

Most newspapers or magazines have reduced or stopped their print editions.

Subscription model works only for niche audience, willing to pay for the premium content and premium experience. Rest of the audience will not pay a penny - they are okay to use the site if it is free but with ads, and many users will use some adblocker, but if site refuses to show content if it detects adblocker, they will simply go elsewhere rather than paying for a subscription.

I don’t think your newspaper analogy works very well here.

Newspapers had willing subscribers especially since they had few alternatives. Their subscriber base was not niche at all.

These newspapers were also heavily subsidized by not only advertisements but paid classified ads.

You either caught the local/evening news on TV or subscribed to a small handful of locally delivered papers. Maybe they also deliver major national newspapers like the New York Times and Wall Street Journal.

The willingness to subscribe didn’t go away, the problem is that alternatives quickly arrived that didn’t cost any money.

Free online classifieds ate the newspaper cash cow. People are often still willing to pay for the services that newspapers provided: just see eBay, Autotrader, and Craigslist. The problem is that your local paper can’t match the product that the internet makes available.