I guess they are also talking about all the old currencies instead or the Euro

Only when they sell one with a landscape mode physical keyboard

If they just start by separating the all-in-one box into a viewing panel and a 'smart'-device connected to each other with a hdmi connection, then the panel can be thin, light weighted, high quality and easily put on a wall, and extra gear can get stuffed away in a corner or so. But the best thing about it would be we can replace the smart-device part with a brilliant-device of our own liking.

I thought there is a company in the use selling such setups...

yes, you may be right, but still, the n900 works pretty well as a phone! I actually prefer it over android.
Speaking of android, I was pretty much dissappointed to discover android linux is not as linux as we know it.
and yes, I want to use my phone as generic computer too, but mostly as a terminal device to my home systems and and hate to see screen space wasted by a virtual keyboard.

I still have my nokia n900 with slideout-keyboard and I really love it.
Someone mentioned the break more easily? Mine still working great after 5 years.
Virtual keyboards have advantages? Well, not sliding out the keyboard should still give you a virtual keyboard.
Autocorrect can also be done using hardware keyboard. Whats different in that respect with virtual keyborads? The system can still use some screen area to show alternatives/corrections you can touch upon.

Another big advantage of slide-out keyboards is the screan real estate not wasted by the virtual keyboard!

I also use a galaxy note 3 but the defualt virtual keyboards are just crap. Swyping does not work for me. I switched to hackers keyboard to make it easier to access not alphabetic characters.

Look at the jolla/sailfish phone for example. It does not come with a sliedout keyboard, but people already started creating a 'other halve' to add a slideout-keyboard.

So I think there is still demand. I would certainly wished a note 3 with slideout keyboard. And I dont mind it beingi a bit heavier and thicker. (I actually prefer it as I'm always afraid these thin phone break when I touch them...)