100%. To add a little more detail, the scope is both broad and deep. Broad - You have many, many new features like WebAssembly or WebXR Device API. All of thes

100%. To add a little more detail, the scope is both broad and deep. Broad - You have many, many new features like WebAssembly or WebXR Device API. All of these are bets and it is hard to know which will gain adoption, so you build things like WebSQL, only to have them abandon for a new winner (IndexedDB). Deep - Rendering HTML5 content with CSS3 styles is such a massive effort. Check out the Servo project, Mozilla's attempt to rewrite the rendering engine in Rust. You have world experts that have already written a rendering engine and after years of progress (2012 - 2018) there was still more to do[1]. TODOs include implement Flexbox, which is core primitive in today's web design toolkit. I'm not sure how feature complete Servo is today, but it is shocking how much effort is required to build a production rendering engine. [1] https://github.com/servo/servo/wiki/Remaining-work https://github.com/servo/servo/wiki/Remaining-work