The Neo900 was I believe nearly 100% bin compatible with our froxen blob ridden Maemo5 Linux so we might have been able to use most apps open and closed.
I would just be happy to have a similar form factor with slider KB a tough bezel and Nokia build quality with OSS drivers for everything where I can run something like Debian ARM though I like the UI of Maemo as an alternative to say Gnome or KDE. Give me real GNU Linux and I will be pretty happy as I was with the Zaurus SL-5500 and N900.
Closed un-upgradeable blob drivers have always been the bump which screws us. Even mainlining the Android kernel would give us a half-assed path forward with nasty blobs for a few years.
Would I love a Neo900 sure, could I afford something at the quote price a stretch, with tech closer to my N900 than current and no idea of a real OS nope. I have owned an OpenMoko, open hardware and software yes, but the experience was terrible, broke my heart but not remotely a daily driver and some of the software even being able to answer a phone call dice roll odds.
So even if we had Neo900s in our hands but without a well developed openMaemo or other OS it would be a crapfest for anything but a dev Tamagotchi that you have to feed hacks every few hours while carrying your real phone too.