What's wrong with "who're"?
Yes, and perhaps more interestingly, what will it look like 500 years from now? Many common modern words that we assume to be self-contained turn out to be pastiches of two or more older words. Like "shire reeve" -> sheriff.
Well I'll be. That is so cool. Thanks!
http://www.etymonline.com/index.php?term=sheriff&allowed_in_...
Edit: Allow me to repay in kind. Did you know that rhubarb is called "rhubarb" because the Greeks thought only barbarians would eat it?
http://www.etymonline.com/index.php?term=rhubarb&allowed_in_...