People buy things from people they like. I don't think this is changing. In many cases (see previous post) we end up buying things without any people involved. At those times, we are buying things from brands we like with processes we like. Well, we probably don't like anything about it much, but we seem to be doing it anyway.
Whenever possible at the grocery store I use the self check out line. The line is often shorter, but the real reason I do it is the experience with the real person has disappointed me so many times. How many times has the check out person said "I can't wait to get out of here; my shift is almost over" when you ask how they are doing? Yes indeed I would rather talk to a machine than someone like that.
When buying something more complex than groceries, say a business service for example, I would much prefer to have a competent and credible salesperson to help me make the best decision. With the right person I get a much needed education, make a better choice, and probably even spend more money. In addition, if something goes wrong I have someone to turn to for help. I am still the buyer and it is still buyer beware, but with a salesperson I have someone with me to help.
Without a salesperson, I become the salesperson -- and that is a whole new level of buyer beware.
Yes we do need salespeople in our business ecosystem.