People in the US were not haggling for anything less than a car in the decades before the internet.
In general the more knowledgeable the dealership/salespeople, the more likely negotiation is possible, especially if you present as a knowledgeable customer so that neither of you are wasting each others' time.
As far as I understood, it wasn’t in the interest of the big retailers to spend time haggling with individuals.
For most people, this has already happened. It's just not as visible as haggle/no haggle (even to the people doing/not doing themselves)
If I walk into a car dealership it's because I need specific information not available online, even if it's just to see the car in person.
What I don't need is a whole sales pitch. That's wasting my time and the salesman's.