If it was possible they would have loved to - certainly by 2012 or so, and more likely by 2008-9. The reason I heard they couldn't is that by that time Flash Player was a massive 10+ year old codebase with lots of parts that were licensed or external, and nobody had ever tracked which parts would be to be relicensed or rewritten.

Source: I worked there at the time and knew the relevant PMs.

That doesn't surprise me, honestly.

I wish they had been able to figure out how to do it, but licensing and patents and whatnot have held back lots of innovation.