Europe still hates Nintendo, but otherwise great sales for Switch. Xbox is dead.

Why do you think that? Do you have any contradictory data?

If you're going to claim something is over/under tracked that you need to give an explanation.

Can someone link me to the thread that shows the weekly sales up to week 8 for all hardware

Switch is widening the lead. Now it’s solidly the top selling console for the foreseeable future.

It’ll be interesting to see what happens when it starts dropping bombs a over the place. Nuke’s like Pokémon are so devastating to the competition that they should be banned by the U.N.

I feel like xbox is over tracked again.

Nice numbers for PS4 and Switch yet again! And Xb1......meh

Where do you feel it's overtracked?
Japan numbers are pretty much confirmed via Mediacreat/Famitsu

NA numbers reaching from 2 Feb - 3 Feb ~ 371k -
NPD numbers (Feb 3 - 2 Mar) leaked at 363k for US which would mean that Canada and Mexico (?) would account for only 8k in the month... so it's probably undertracked if anything.
EU + RotW is the only unknown and considering it's up both in the US and Japan it's not impossible it would in EU and RotW as well.

Based on what? Jpn is a non factor, numbers are low in the EU. NA is tracking quite decent and it matches with the NPD numbers.. even likely it's a bit undertracked in NA.

what will happen to switch when next gen consoles launch this year or next

We can make predictions but we will only find out when it actually happens. But I remember lots of people saying that the Switch wont do well because the XboxOne and PS4 have already released and built a huge game library. 

But what actually happened is that lots of people doesnt mind double dipping this gen. The Switch was not a direct competition aginst those 2. It had the handheld feature and exclusive games to stand out from PS4 and XONE.