I do think Windows will become pretty irrelevant over the next 5 years, as Android and iOS get owned by billions of people. However, I agree that right now and for the past few years, there's a very strong bias towards Apple computers in Silicon Valley and in media offices, and they might think "Apple is everywhere", even though it's not.
If Apple keeps curling up in their luxury niche it will be iOS that's going to be irrelevant in 5 years.
And Microsoft will start to decline if they don't go after SAP's and Oracle's enterprise applications business before their server-side stuff becomes a low cost cloud based commodity.
I think both Apple and Microsoft are going down. Linux will rule the server side and the client side in the shape of Android/Chrome OS.
