> Given the existence of standards, there's not a lot of 
  > room for innovative behavior.

This is incorrect. Servo, with its goal of being fanatically concurrent, is forging new ground in discovering exactly where the HTML specs both admit concurrency and where they unintentionally demand serial behavior. Browsers of its ilk, regardless of adoption, will be instrumental in informing future standards such that they are not accidentally hostile to concurrency and parallelism, thereby clearing the way for widely-adopted engines to implement such optimizations at their leisure.