Hmmmm, they didn't put the number of php web sites on there. The chart would have to have been a logarithmic scale. The other technologies would not have even come close.
I am thoroughly agnostic as I have architected in both. I do think that java as a language is here to stay due to the gradual emergence of Grid computing. That approach is just coming to the fore but will pick up steam in the rest of the decade. While Java will be there is the need to do realtime migration of processes/threads across machine boundaries and using the JVM to do so is becoming a common technique. Right now they use the built in debugging hooks but look for the Java community to build services into the JVM that handled this in and elegant way.
That being said, as web services become more and more common then is will not really matter what technologies underpin the services. Many production systems will be an amalgam of services "rented" from middle tier vendors. It will be quality, predictability, security and speed. That wins the day and buyers will manage through SLAs. They will not care about the technology below those SLAs.