There's nothing hollow about it. PS4 and Switch sold through similar numbers in calendar Q1 2018 while the PS4's release schedule was notably stronger. The low PS4 shipments during the same quarter are the result of too much excess stock from the previous quarter.

The new forecasts put Switch alone ahead of the PS4, something that hasn't been the case in the recently ended fiscal year.

It is clear that the low shipments were due to last quarter, because we have two facts that support such a conclusion:

1. Sony provided sell-through numbers for the end of 2017. Those put the gap between sell-through and shipments at 2.9m which is higher than normal.

2. Sony's forecast for the recently started fiscal year is 16m, a number that doesn't suggest low stock levels on a global scale at the end of the recently ended fiscal year.

Japan isn't an indicator for global stock levels because neither America or Europe have come even remotely close to having shortages. Additionally, the stock that has been missing in Japan is only around 100k units (missed out sell-through + units to put on shelves for retailers) which has a negligible impact on worldwide shipments through a whole quarter.

Last year was shortly after the launch of the PS4 Pro and Sony had yet to figure out appropriate production levels for their two PS4 SKUs. The PS4 Slim was in abundant supply, the Pro was in short supply in early 2017. This means that of the 2.9m PS4 shipped during calendar Q1 2017, the Pro SKUs ratio had to be disproportionally high out of necessity. Retailers ordered a much lower amount of standard PS4s than usual, but they had to order a lot of PS4 Pro consoles to get the product readily available in their stores. This situation did not repeat in calendar Q1 2018. That's why this year's 2.5m in calendar Q1 aren't unreasonably small.

Nice prediction, Rol! I'm pretty sure I posted somewhere in this thread agreeing with it. As I said, Nintendo's aim with the Switch needs to be the DS and the Wii, not any console below 100m units.  So, after the Wii U disaster, Nintendo is now the market leader again.

Right now though, I think they've had some missteps again. Labo was supposed to be their big casual hit but once again, Nintendo proved that they don't understand the mass market. Also, the release schedule is heavy on modern 3D Nintendo titles (Yoshi, Fire Emblem, Smash) but I don't see much classic Nintendo this year. I predict this will impact sales in the long run. If they want to match DS sales they will have to deliver for the classic Nintendo fans and the expanded market as well. Otherwise the Switch won't be growing the market but simply gobble Nintendo's already existing handheld and home console markets - stable, but not exciting.

What exactly is this based on?

They have put a big marketing campaign behind Labo and demoed it at various events but the market didn't react well to it. They treated it like one of the big guns (the only big new title besides Kirby in the first half of the year - they wouldn't do this if they thought it was just a niche thing) but the mass market wants different kinds of games. It's been like that for a decade now, Nintendo didn't understand the success they had with the Wii and DS, which is why we went from the Wiimote to the Gamepad and from the Wii to the Wii U.

FINAL UPDATE: April 27th, 2018

Both Sony and Nintendo have announced their results for the full fiscal year.

Sony: 19.0m PS4s, Vita undisclosed.
Nintendo: 15.05m for Switch, 6.4m for 3DS. Total: 21.45m.

In the final quarter of the fiscal year, Nintendo grew their lead of 1.48m to 2.45m before PlayStation Vita is factored in. This value of 2.45m makes it a little bit difficult to determine if Nintendo's win falls into the 1-2m range or the 2-3m range, but either way, it's certain that Nintendo is #1 again. I'll say that Nintendo's margin of victory falls into the 1-2m range, because it isn't really something that is worth fighting over and it has been a very long time since we've heard anything about Vita sales outside of Japan.

As you can tell from the headline of this update, this thread has run its course and won't receive any further updates. A year ago this was a very interesting comparison, because anything other than a Sony win was going against the majority opinion. Now there's no question anymore regarding who is the #1 in the console business, because the forecasts for the fiscal year ending March 2019 are as follows:

Sony: 16m PS4s, Vita undisclosed.
Nintendo: 20m for Switch, 4m for 3DS. Total: 24m.

That's such a big gap between forecasts that it is a foregone conclusion who will sell the most consoles in the fiscal year that started this month.

The reason why there's no new snapshot of the poll in this final update is because only 24 new votes have come in during the last three months. Those are too few votes to have a meaningful impact on the results of a poll with over 900 votes in total.