Suppose you came to work one day and somebody else was sitting at your computer! This is a ridiculous, outmoded fear. Because what you should really be concerned about is that NOBODY will be sitting at your computer because your chair is gone and your computer is running itself.
This is one of those perennial type of apocalypse jobs stories that seem like they must be true and simultaneously seem like they won't be true, because they rarely are. Still, it's hard to spot the obvious flaw in the logic. Kids in school don't seem to be getting any smarter, but computers sure are. What's that formula, again? Computing power doubles every two years and doesn't leave crumbs at its desk? It's not that computers are going to outclass us someday; they already have, but we haven't realized it yet because of our slower processing capacity.
So, yes, one day machines will do our work for us, but we never figured out that little paycheck wrinkle. Slow processing capacity, again.