Not all humans have equally capable literacy and industrial background.

To use current Top AI SaaS models for coding, the users have to write text prompts. There is clear difference of result by programmer and non-programmer.

Image and music generation have exactly same skill gap.

So most human don't directly use AI even if it's available to all 8 billion population.

But I really doubt we will have such all humans use AI.

The current estimate said 80% of world population own a cellphone. 50% own a smartphone. Even the cellphone is not reached 100% share, how could AI with current top model quality reach 100% share?

It's "what if" thought exercise, doesn't need to be an accurate (or realistic) prediction.