Nokia used to make boots (foot wear) before they started making phones.
Today, only Apple and RIM make their own phones where they also own the OS that runs on them.
Nokia used to have Symbian, but are now using Microsoft.
RIM, with their BNX OS, renamed to 10, is a phone and a tablet OS. Computing technology is going to continue to improve at about the same exponential rate as it has been for the last 40 years, for perhaps another 20 years. RIM can compete because they have a lot of patents, or IP. The world changes and no one can predict the future. And where I am going with this I have no idea