Linux vs. Windows and OS X: it is the economy that will be the driving factor
Step outside of pure technology for a minute, and think about the global economy and were the buzz is right now: the US is educating a very small fraction of engineers and scientists as places like China, India, Europe, etc. The largest growth will be in what are now poorer countries, but expect a more level playing field in the future. There is a good reason why high technology companies are increasingly setting up research labs outside of the US: less expense and a good supply of highly motivated and educated talent.
Using Linux in developing countries makes the most sense: computer science students get free access to source code and end users can run on much cheaper hardware using free software. As more creative work is done outside of the US, scientists and engineers will naturally use what they have used in school: Linux.
Long term, I expect to see an upswing in technology in the US: with the amount of perceived (fake) wealth in the US (from people pulling $400 billion a year in equity from their homes for a higher lifestyle, etc.) many young people simply lack the motivation to work at science and engineering in school when they see lucrative careers in real estate and other fields that require training but not too much education. Who knows when the crash in the US economy will come, but when it does occur it is likely to make the "comfortable" recession of 2001 look like a picnic. Usually success requires education and hard work, and in the future when we in the US are climbing out of what I think will be a very long economic downturn, I also believe that poorer economic conditions in our country will motivate both student and workers. During the upcoming economic slump in the US I would not be surprised if Linux becomes more popular with end users for the same reasons that Linux is gaining in popularity in developing countries right now: families trying to hold on to their homes and meeting other mandatory expenses might look favorably at $200 Linux PCs.