Less than 1.5M yet to be sold (shelves/transport) is really no big deal.
When you have a system that sells well and have a healthy production you'll very likely have a good amount of it always being transported to several retailers everywhere and waiting for you to pick it.
As zorg1000 said the PS4 had double that amount of its peak some time ago (which is honestly high, no wonder it started to decrease).
Better to have the system being widely available than widely out of stock.
The problem is when it does stay in the shelves for a long time and next shippments are small because of it, then it was overshipping or losing sales volume, like those AC Unity XBO bundles.
PS4 and Switch shippments are really just fine, don't worry, actually XBO also should be since last year, it's just that we don't get to know about them officially because it was a big dissapointment early in the gen.