These datas show that for 2019 the Switch is exploding only in Japan (+45-50%) and just having a noticable increase on other regions...I wonder if European and RotW numbers are not dramaticaly undertracked.

LTD shipments by December 31st 2018 were 32.27m, sell-through according to VGC was 29.48m by December 29th 2018. Adding a couple of extra days of sell-through leaves a gap of more than 2.5m units, but Switch's stock level should be ~2m based on how much it sells per week and in how many countries the console is officially available in. Retailers tend to have stock that lasts them 6-8 weeks and they place new orders accordingly.

In order for shipments and sell-through to be equal for the current quarter, VGC's LTD estimate by the end of 2018 has to be wrong. Which is possible, but I said "if we go by VGC" and that means as much as "assuming that VGC's numbers are correct," so that's what the rest of my post goes with.

I see that you've been talking about fiscal year shipments as high as 18m, but that's not going to happen if VGC estimates are reasonably accurate. A note on forecasts: In the range that Switch sells, adjustments are made in increments of 0.5m, so Nintendo could have gone with 17.5m for their revised forecast. The reason why they adjusted down to 17.0m is that it looks really bad when a company can't even fulfill a revised forecast with only three months left in the fiscal year. Nintendo had to ask themselves if they are absolutely 100% sure that they can hit 3m in fiscal Q4 and they weren't confident that they could do it.

You are making the same mistake again. The proper comparison is always LTD sell-through vs. LTD shipments. The key point is that retailers tend to maintain a stock level that lasts them 6-8 weeks in order to be prepared for sudden surges in demand; if they ran out of consoles, a potential customer would do their business at a different store.

A console that sells 250k units per week worldwide will have a bigger gap between LTD sell-through and LTD shipments than a console that sells only 150k units per week. There are times when retailers over- or underestimate demand for a console, so the following fiscal quarter will see a correction due to retailer orders. VGC's estimates point to a slight overestimation, so for the current fiscal quarter sell-through can exceed shipments as retailers scale down the stock they have on shelves and in their warehouses.

There's no definitive answer here, because VGC's numbers are estimates and adjustments can be made to older quarters over time. My main point has been that you should be a bit more cautious with your expectations, because there are factors that make a fiscal year shipment total of 18m a stretch despite strong sell-through at the moment.

In your graph you already have Switch's stock on shelves and in transit at 2.4m which is on the high side (you are actually missing Switch's launch quarter for the cumulative total of the gap between sell-through and shipments). The gap isn't going to increase with each passing quarter, because that's not how retailers work. It's more likely that the gap decreases by the end of this quarter, so if we go with your VGC projection of 3.46m sell-through for the quarter, shipments should be expected to be in the range of 3.1-3.3m rather than 3.6m.

An example that might help here is that the PS4 had a gap of 3.7m at the end of calendar year 2016, according to Sony's own sell-through and shipment announcements. The January-March quarter of 2017 then had low shipments because retailers had to correct the amount of stock they carried. That's the kind of situation that leads to the occasional quarter where sell-through is greater than shipments.