There is so much.<p>* I would create an alternate trust model for TLS not using certificates.<p>* I would make WebSockets the default transmission medium, not HTTP (or its variants).<p>* I would make JavaScript strongly typed, like TypeScript, and eliminate implicit type coercion.<p>* I would throw away a substantial amount of HTML5. HTML should be tiny, strict, and self validating.<p>* There are native methods I would add to the DOM.