As someone who's never preordered a console and has owned every console day one, not worried. I'll be able to walk into any store and grab it day one. Just like with every console in history.
With new tech I think there's a couple of factors. One is just that it takes a bit to ramp up production to mass produce a device that can meet the demand. Two is that you definitely don't want to overdo it and wind up sitting on a mountain of inventory that you can't sell.