if you think that something that runs in a dusty box can do everything that something that runs in your hand can, you should find other work.
can php animate your site?
can php play a list of podcasts?
can php make simple calculator that behaves like a real 99 cent one?
can php create a whack-a-mole game, simon, snakes, or any action-based game for that matter?
can php tell you of a mistake before you sumbit the form?
can php underpin drag and drop applications?
can php show your exact location on map?
can php build apps with async background processing?
can php deliver a desktop notification when news breaks?
can php use rich GL graphics with hardware acceleration?
can php apps allow you to edit, save, and load data without an internet connection?
can php auto-fill suggestions on a from based on what the user is typing?
can php play fullscreen video?
can php run out-of-the-box on every PC, tablet, and phone made in the last few years?
can php make video chat?
can php provide oAuth and other social logins?
can php display rich tooltips with clickable elements, like you see on hulu?
can php re-sort a visible table without wasteful IO, parsing, and re-rendering?
can php make a basic text editor with selection processing like this reply box has?
can php make a speedometer that tells you how fast you are driving?
can php store DB info on the client device, where it's available instantly without the web?
can php unobtrusively update the visible page when someone leaves a new comment?
so, let's try to be fair, what can php do?
can js grab a file on the server? oops, yes it can.
can js grab info from other sites and store and process it? sometimes, but php almost always can.
can js fetch a single student's info from a DB of 50,000 students? node.js can, but "no" is likely most correct.
can js integrate with existing AD and other enterprise logins? not really.
can js send email? not really.
can js send a song from one PC to 50 other computers? barely, webRTC is young...
given the choice, and especially now that i can leverage js skills on the backend using asp and node.js, i don't see too many advantages left for PHP, compared to the "wow" factor of local computing.