It's the biggest cost in the distribution chain.
That means there's room for competition.
You aren't going to trust moving 100 million in product strictly to robots for a long time. And that's just a small business. And there's a lot of them.
>why wouldn't the advantage go to a few big players, rather than a ton of small ones?
Because it's still way way cheaper than labor. Maintenance means you're paying for one guy's medical benefits instead of 20 guys, for example. The labor is the cost that's difficult to overcome and gives the bigger players an advantage. When that's stripped away, it's possible to compete against the bigger guys.
Cheaper than existing labor costs, loans can overcome capital entrance, and you can afford to pay on them when there's a smaller operating cost, plus they have some fixed ROI. Existing need for more warehouses, combined, I don't see why we wouldn't see more warehouses. Of course we will.
Look at middle America. Almost every metropolitan in the country is building warehouses in and around their airports. Some indeed are Amazon's and other big suppliers, but the majority are not. They are small storage and shipping outfits. Don't forget who supplies Amazon!
Also, the push for more condensed housing means fewer people per household which means more duplicate junk per person as they won't share with another household, obviously.
Growth means warehousing. There's no way around it. Unless we will manufacture domestically, that demand isn't going anywhere.