I think feature wise HTML5 can do everything that Flash did and even better, but I still think that ease of use is an important factor when comparing them and HTML5 is not easy to use. HTML is already taking over Flash with only that niche market of browser games still relying on Flash heavily. I don't see Flash content being rendered in HTML, there is no incentive in supporting it neither by Adobe nor by the web community. What I think will happen is that making games for HTML will get easier and with WebAssembly there will be a strong push in performance hungry applications (that includes games) in the browser, and maybe that will replace the remaining bits of Flash in the web .