It doesn't really matter what you want though, only what CEOs want and that's low costs. I can see a combined shirt folding/traffic merging platform taking off.

You misinterpret "want" here. My intuition is that you create huge problems for people context switching like this repeatedly for quick tasks.

but call center are still mostly single client even though it would be cheaper for any worker to be able to answer to any call. So clearly the expertise and context trade off is too big to be worthwhile

CEOs are loser nobodies. Real influence is with owners, boards, investors.