[Klaus]

Well, with that amount of lenses, it'll be for fanboys only in the beginning.

Rubbish. It depends how well the DSLR lenses will be adapted and soon the cameras will be for everybody (owning Nikon and) shooting often in LiveView or tethered or using it for portrait work. People who still have a bunch of Nikon manual focus glasses. Sorry to sound like a fanboy, I have more concerns about the success but missing lens choice is the least.

I see them as something interesting for people already in the Nikon system. My doubts are:
The first models will come with shortcomings, miss modern features, very probably can't compete with state of the art ML AF - so what reasons should one have to go Nikon instead Sony?
That Nikon is able to do something mirrorless - the 1 system is the proof. Unfortunately also the proof of solid misconceptions. Will they mess up less big time with FF?
Can we expect more than traditional ideas? 95% sure NO
A Kaizen concept like Fuji has to at least make the investment a bit more valuable?
A touchscreen which works well - and more important a better interface?
Better WiFI app?
Enough battery capacity and maybe someone at Nikon found out that USB can be used to charge a camera?
Seeing how Nikon goes the simplest and most expensive, yet wobbly way to design battery grips, can we hope for a useful one with added functionality?
How big will be the video shortcomings?

I don't even dream of Arca compatible bottom and side plate or of infrared focus patterns, of a menu system adjustable on a tablet or PC instead of the tiny screen, a real useful tilt/swift display. Knowing Nikon they will just stuck to their traditions and erase the mirror... But I'm open to surprises.

Adapters are and always will be an excuse but not an argument.
An adapter is always a compromise. Back in the days I also used an adapter on the Sony NEX. That adapter transformed the camera into a Sony SLT with essentially no AF penalty compared to the native SLTs. Even so it was just nothing short of alien and utterly pointless compared to native lenses. DSLR lenses just felt ridiculously large and unbalanced on the body.

Is that adapter relevant to Sony users today? No, it obviously isn't. 
Are FT-adapters relevant to MFT user today? Nope.
Do Fuji users care? No.
It may be that a few users use adapters for exotic lenses but these 3 systems are pretty much complete. There is just no need anymore for legacy lenses.

If you really buy this Nikon camera from day one, you are a fanboy. If you wanted to use Nikkors on a mirrorless camera, you could have done so for years - there's a Nikon AF-S adapter for Sony E mount adapter after all.

Anyway, there's nothing wrong about having a brand-affinity.