As far as I remember, Rasmus worked on that for PHP 7 and the conclusion was: excellent for benchmarks but no improvement for real world web applications.
I understand your argument "It opens the door for PHP to be used as a very performant language outside of the web." but I'm really not sure it's worth it.
I understand your argument "It opens the door for PHP to be used as a very performant language outside of the web." but I'm really not sure it's worth it.