However, I fail to see how this will improve the overall quality of PHP applications, nor how it is a return to "the basics," or how it will help maintain the myriad content management systems that are currently out there. Care to elaborate?
I dunno, I guess I just think a functional paradigm could offer a faster and easier way for retooling existing PHP applications/frameworks that focus on what the application is supposed to do rather than how it's going to do it. Let PHP's extensive library worry about the system's protocol; this could help leverage your end-product as an API first, rather than opting-out of any further abstraction just to get what you think you want.
I dunno, I could be way off; I just think PHP is so matter of fact that attempting anything as abstract as what a purely functional language is capable of is nearly inexpressible.