In a recent post from Frank Karlitschek he speculates about the future of PHP and what when into their (ownCloud) decision to go with it as a primary language. The post also proposes several changes he'd also like to see in the language to help improve it in the future.

PHP is not the most hip programming language in the world. Actually the opposite. It has a relatively bad reputation. I personally was never a big fan of choosing the technologies based on what is cool or "modern" or in vogue. I think there are different technology for different jobs and they should be evaluated objectively and choose without to much emotion involved. So I don't understand the religious discussions why tool x is always better than technology. I think it is all about the right technology for the job after a fair assessment of course. So I'm still very happy with this decision to use PHP. So far we have not seen any bigger architectural technical problems [for ownCloud] that we can't solve with PHP.

Among his suggestions for change are things like enhanced security features (and better teaching around best practices on the topic), a simplified compile and runtime configuration, function/class naming inconsistencies and the introduction of static typing. It's his opinion that this list can help PHP "move to the next level". There's plenty of comments on the post, both supporting and refuting the opinions Frank has included in his list...be sure to give them a read.