What gives you any reason to doubt that they will?
Things don't enter the public domain anymore, sorry.
I'd actually be pretty happy to pay a small subscription to websites that I use all the time, and that seem to be worth it. Of course, there are a lot of websites that would die very quickly without advertising, and I don't object to that at all. They can go, and that is fine.
I think a reasonable subscription to a website I really like would be something like a $1 to $1.50 a month. If enough people are paying, that can easily cover the costs.
Of course I'd rather have those websites supported by voluntary donations. Lets not pretend that it doesn't work, just because Wikipedia are hopelessly greedy and over-ambitious. For many websites it can work fine. I know at least one for which it has worked for more than a decade.
For me if I have to use cash I'm already against the purchase. It's horribly inconvenient for me, and isn't accepted for online purchases which is where I do all my important shopping other than clothes and groceries. Since I can pay for both of those things on my card as well as at pretty much any restaurant, I've got no need for cash that I can see.
Even convenience stores are happy to accept a card (with no surcharge) for very small purchases. I admit that has changed in recent years, and until that change I did grudgingly have to withdraw cash to shop for those items.
I don't really care to carry currency which can be lost or stolen, and then never recovered. If I lose my card, all I have to do is contact the bank and let them know. They will cancel it for me and I can soon get a new one. Under those specific circumstances I would use cash, of course. Since I am deprived of all the better options.
I see things are different for you, but I prefer to handle as little cash as humanly possible.
The moon is made of green cheese. -- John Heywood