Why are you isolating a single algorithm?

To show that quantum computing only helps with very specific parts of very specific algorithms.

A QC is not a CPU, it's not a GPU, it's closer to a superpowered FPU.

If they would offer speed benefits, then why wouldn't you want to have the chip that offers the speed benefits in your phone?

if somehow consumers could have access to technology in their phone that would offer performance benefits to their software that they wouldn't want it.

Because the same functionality would be available as a cloud service (like AI now). This reduces costs and the need to carry liquid nitrogen around.

The issue is not that quantum computers could not offer performance benefits in theory.

It is this. QC only enhances some very specific tasks.

It is the same with GPUs. A GPU can only speed up certain problems. You have libraries that only call the GPU when it is needed for certain calculations.

Yes, exactly my point. QC is a less flexible GPU.

I don't see why consumers wouldn't want it.

Because they would need to use the specific quantum enhanced algorithms frequently enough to pay to have local, always on access.

They will likely remain something largely used by businesses but in my view it will be mostly because of practical concerns. The benefits of them won't outweigh the cost anytime soon.

Agree. Unless some magic tech, like room temperature superconductors, turns up there will only be quantum as a service supplied for some very specific business needs.