Yes, I realise Nintendo was trying to court home comsole players. After all, it is the home console Nintendo fanbase that is most likely to feel abandoned by Nintendo moving to Switch as its only 9th gen offering. And it is a genuinely 9th gen handheld. And, as you say , Nintendo is still interested in 3DS having one final decent holiday.  So I can understand Nintendo's rather hamfisted PR tring to make Switch out as a home console first. But when you look at the promo video I think a lot more time is spent showing Switch being used as a handheld, i.e. look at all the cool ways you can play this on the go. And if you apply any sort of logic to the situation you will look at Switch in the "right " way despite Nintendo's recent PR.

They don;t want 3DS

For Nintendo themselves yes it is

ports of major PS3/360 games did nothing for Wii U, why would ports of major PS4/XBO games do anything for Switch?

It would be a hard sell to say this is an actual full gen leap from Wii U.... So yes it is may be a bit much.

Yeah, but honestly if they had a problem with replacing 3DS, they should have waited until next holiday season to replace both at once.
If anything, they could hold back some mid-year Wii U games to launch them at holiday as cross-games with Switch.
And the delay would if anything help them get a better product, with a lower power 10nm process, maybe cheaper RAM/flash/screens.
(I'm somewhat holding out on whether they manage 10nm by next spring, but they could for sure do it, and probably better process, by Xmas 2017)...

It looks like your comment on 3DS at the end of your post was cut off or something...

Nintendo has been slow-pedaling their generation upgrades for quite a while, from GC->Wii->WiiU now to Switch.
We are now just at the point where the implications of that mean their home console is now high-tier handheld level.
It's not really a new trend for them.  
And to be fair, Wii U was very short vs. Sony/MS and previous Wii gen, so relative upgrade of next gen is logically smaller.

4GB isn't bad for a mobile device, which s basically what the Switch is. Third parties might be able to manage. After all, the Xbox 360 had twice as much ram as the PS3 and third parties managed that.

But it's still lagging behind products that will be in their forth year when NS release. If they were on regular gen cycles (5 years) generally we'd be hearing about all the 9th gen consoles. This doesn't even match up with 8th.

Nintendobis very secretive on this matter so we have to wait till january 12th to see if there is so secret sauce in the switch 

But i think it will be priced well and it will be a success

I think it will be priced well and be a success as well, it just in no way will be powerful.