With the evolving of smartphones and tablets, there will be more and more people stop using computers.
I agree, somewhat sadly.
Programmers, Photographers, Graphic Designers, dedicated gamers, video editors are some of the people who NEED a computer. That number is shrinking every year. Already most people can do most of what they used to need a computer for on their tablet, and I'm being brand independent here-IPad, Surface, and the combo notebook/tablets that most computer manufacturers are pushing to compete with the tablets.
Games? People are mostly choosing Sony/Xbox/Nintendo for gaming. Is it as good as a high end computer? No. But people don't care. And you can use your tablet for gaming as well.
Surfing the internet? Tablets work as well as computers in most cases, they're portable and the batteries last.
Email/documents? You can read any email or document on your tablet. And with a light weight keyboard you can type on one as well. Most software either already is or soon will be cloud based. You don't need the resources you used to for word document and other software.
Are they perfect replacements? For a lot of people the answer is already yes and every 18 months, when new tablets arrive fewer people have a use for a computer.