Canvas is too slow and handles text rendering poorly. If browsers really want to take another step in that particular direction, they're going to have to expose a lower level API for graphics and text rendering.
Maybe. OpenGL has a lot of history and baggage. I'm pretty sure the current browser engines don't use OpenGL for 2d graphics. I think they still use Skia (Chrome) and Cairo (WebKit). It could be as "easy" as allowing calls to be made directly to those graphics libraries in WebAssembly.
