I think this is a relic of the past. My last two car purchases have been straight forward: I walked in and told them what I was willing to pay for the car. One dealer couldn't do it, another could. In fact, this dealer showed me their little spreadsheet of costs associated with the car and said, "This is what we'll make on this car at this price. If I go any lower than this it is no longer worth it for us to sell to you." I make the purchase and pick the car up the next day. The car dealer business is pretty competitive, at least where I live.
There is so much information available to consumers that there's no longer any reason for the process to be very complicated or opaque. Sure, you might not want to "negotiate", but then you're welcome to go pay retail ("sticker price") like you would anywhere else, including Tesla. If you do that you'll be out of there in a heartbeat at that price (and the dealer will love you).
I don't car what happens to car dealerships, honestly. I just don't find them to be such a problem.