Right, but what about the time when there's nothing sufficiently valuable for those people to do? Historically, we've been very able to replace old jobs with new ones - technology simultaneously freed people up and created new job growth segments. The question is whether technology is still capable of creating enough new jobs.
Luckily, human beings have essentially unlimited desires. For this reason, there will always be sufficiently valuable things for people to do.
If there is truly nothing valuable for an entire population to do, ie if machines can fulfill every desire we can dream up, it means humanity has finally created utopia.
The problem is not utopia, it's the situation where there's nothing useful for, say, 20% of the population to do. I think there's plenty for the highly intelligent and well educated to get on with, but for those without (and perhaps unable to achieve) that level of education, it's a tougher situation.
Even if you presume all those less talented employees are mindless drones, if you can provide the same service with fewer employees, you now have all the value created by that service, plus you have all those extra mindless drones to go produce value someplace else.
As to your second point, I can't imagine that's what he's really thinking. The few talented people who create the twitters, iphones, etcs, are far outnumbered by the millions of less-talented people who actually use those products.