What happened to Linux?
Mark Shuttleworth, the founder of Canonical, the publisher of Ubuntu, has given up on the idea that Linux (which Ubuntu is based on) will ever supplant Windows, saying that if any OS will be the next big thing it's Apple's iOS or Google's Android.
While there remains talks of an Ubuntu Phone OS, it may be too little too late.
So what happened?
Lots happened and none of it good. Linux never got past serious server room usage because it was never marketed to be more than a gimmick – an alternative for cheapskates.