Microsoft is a railroad company in the early days of the automobile. They're a typewriter company in the early days of the microcomputer. They're a sailing-ship builder in the early days of steam. They're important currently, but they're being left behind, and they have not positioned themselves to get in on the new stuff.
It takes a long time for changes to happen. Microsoft can live fat off the PC for a long time to come. But they will slowly slide into irrelevancy if they stick with that.
The comparison to railroads is apt. Railroads are still immensely important, even if people no longer romanticize them. Innovations in railroad technology are still very important. The financial difficulties railroads faced in the middle of the 20th century had more to do with the government promoting automobiles than with the superiority of cars and trucks. If Microsoft is the technology world's' equivalent of a railroad they are in a pretty good position -- they might not be the company everyone is talking about but they will be the company that everyone is dependent on.