And let's be honest, most ads are total garbage.
If users want your service, they will pay for it. If they don't, well then your services is not needed.
So the site will die, because nobody thought it had any value.
What's the problem?
I really don't like your definition of 'free'. wikipedia has been relying on donations for quite some time. guardian.co.uk is one of the recent examples asking for donations and working out for them.
>science articles
Ok that has to be a joke, the paywall journals subscriptions are nothing like ads.
Please, don't conflate any pay method with pay wall (which is a pretty good one). If business cannot retain itself w/o breaking the law and has to shove unwanted images/videos/etc. straight in the face, it may as well not exist. The ads have degraded user experience in so bad ways that having a page with little content and 'next' button just to show more ads is pretty much the norm now.
A somewhat related note: Relying solely on ads is a bad idea. Personally, I'll install an adblocker on every PC I get access to (family and friends stuff).