There is no technical reason why this couldn't work, but my guess is that abstraction libraries will be necessary because Apple and Google won't be able to a ag

There is no technical reason why this couldn't work, but my guess is that abstraction libraries will be necessary because Apple and Google won't be able to a agree on a common API. I kinda agree because having to standardise HTML, CSS and JS is hard enough and the browser makers don't wanna open up another battle front. Also, being able to tailor the API tightly to the underlying browser will attract developers and therefore enable more competition. Good times for add-on developers!