Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Mark Shuttleworth, the founder of Canonical, publishers 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.
I still keep a machine loaded with the latest Ubuntu and have always believed that it was a smart idea to outfit a large corporation with Linux-based PCs and free software. It would save a lot of money, perhaps millions of dollars, and would protect the employees and the company from all the malware written to attack Windows while being just as efficient.
I don't believe that anyone in the Linux community has ever spent a dime selling that idea.