All my HTML still works. Just don't go overboard with frameworks and Javascript.
The very browsers that pushed that change founded Let's Encrypt to provide free certificates prior to pushing sites towards HTTPS. That's the opposite of a profit motive. There are also more free alternatives like ZeroSSL since.
To be clear, what I mean is that forcing HTTPS-only is something that is required by profit motivated corporations. They see the potential risk of an HTTP downgrade attack as being enough motivation to completely kill HTTP. And unfortunately even Mozilla is going along with it. HTTP has it's place for human persons and human person run sites. It allows free communication without having to exist only on the whim of some CA or your mega-corp browser's decision if your cert is too long, too short, or too something.
I did not mean that the founding of LetsEncrypt was profit motivated. LetsEncrypt is good for what it is. But forcing HTTPS and not allowing HTTP at all is very, very bad for the web. Especially since cert CA usage follows a powerlaw like normal and nearly everyone centralizes in LetsEncrypt.