I wouldn't complain if a better server-side language came around (not a big fan of Ruby's syntax, but Google's Go looks enticing), but until then, I've built incredibly complex apps in PHP, and rarely do I run into a limitation of the language. My biggest issue in the past was the lack of namespaces, and 5.3 has those.
I think the best thing you could do to get a new language as popular as PHP isn't to evangelize, or even to make the language dead simple, but make it dead simple for administrators to add support to a typical shared hosting environment.