I think that trend has ended somewhat now. PHP is no longer uncool, but something useful you can use to throw your web-fronts together.
Alternate VMs are not a new trend btw. In 2008, sort of hitting a wall of performance with APC, I started writing a basic block JIT for php bytecode, which would replace small arithmetic centric blocks of code into x86 native code - hooking into the PHP CGOTO engine.
But the essential problem with anything you write is compatibility and having to reimplement things bug-for-bug.
HHVM showed somewhat that people would tolerate some compat breakage, if people got 100%+ CPU savings.
And HACK-LANG clearly shows a different direction (risky, because if FB drops HACK, it's worse than Zend dropping PHP), which is being picked up by people who want to avoid some of the madness of PHP (i.e absolute type hinting needs generics).
(about the API mess: I've been programming in PHP for over 10 years and still i have to look up parameter order for some of the string functions)