It's probably safe to say people have been wondering that for decades.

Remember there are lots of NP hard problems, that soak up any additional computing power you throw at them. A lot of them are very important (placement in EDA for example). Supercomputers today are already 1000000 faster than current desktop computers and still they are no where near where we would want them to be (to simulate the earth athmosphere at sufficient resolution for example, or all the neurons in a human brain)

I bet at that time there will be new workloads and tasks that demand even more computing power, like today.

Yes. Even with 1000x computing power, having twice as much as that is still valuable. There are any number of applications which will literally use all the computing power you can throw at them.