There is no need to aim for mass adoption. Make it a standard for whoever wants a simple html environment. It could be situated between gopher and the full html

There is no need to aim for mass adoption. Make it a standard for whoever wants a simple html environment. It could be situated between gopher and the full html spec. People use command line based browsers. A limited browser is usable, just not for full web apps. To start it, offer a website that checks websites for their compliance. At the same time, let webmasters register their site so that you can offer a directory of available content. If you want to monetize your project, offer a search engine with ads for all sites that passed the test. The icing on the cake would be a proxy service that transcodes complex websites into the simple standard by analysing the site with a headless browser.