I love the idea of wasm allowing other languages, but it's going to take at least a decade to be usable for anything aside from heavy number crunching with C++. For a webpage, replacing the DOM with UI toolkit X is a pipe dream with problems ranging from aria/accessibility to web crawling and indexing issues.

Adobe won't be bringing flash back. It was basically just ES4. ESnext and HTML5 have almost all the good stuff plus quite a bit more while having far better performance than flash could achieve.