Anyone can look forward 5, 10, 20, 50, 100 years and make predictions - but I doubt many are going to be that accurate, especially when technologies that didn't exist at the time totally transform how people operate.
I mean, we're living in an age where - in theory - a lot of us could work from home and teleconference, but it hasn't happened for the most part. People want social contact, and those who do get to work from home probably travel around more for leisure.. and of course, now we have social media bringing everyone closer together, people are travelling far further to meet up with people etc.
Predicting a simple increase in passenger numbers, based on an increasing population, is probably one of the easier things to predict - but beyond that, how much is mere guesswork?