I will reply direct to save space Carsten. I never did think but had to ask the motivation money has to you but as for the "red tape" involved to open source i think will get a push from the Poll and this community and as it takes time it could be a while before we get anything but i am sure something will happen sooner or later.
I also think by looking around if anything the N900 will actually gain popularity and will definitly become a collectors treasure simply because i cannot see anyone making such a device anything close the this one so even with dated hardware it will still increase in value in my opinion. I agree with the your freemantle points but as this is Maemo.org and as long as people actually see some progress happening i very much doubt development will cease for a long long time yet.
I think it will boil down to open source replacement design specific to this device from the Communities own dev's so you will see a Maemo version adaptation based on those factors in the future.