Call me a troll if you like, but I will jump into this conversation slightly off-topic, as I find the topic to be slightly off-beat. Nokia don't have a need for a new OS, what we need is new top devices from Nokia (ones that aren't stupid feature phones). A good range of decent devices with the same OS (or two OSes if you wish, bound by Qt).

I know nobody here pays attention to me when I rant about DEVICES, because many people here are developers and care more about software. But, this is putting the carriage in front of the horse. Hardware always comes first. N900 alone doesn't cut it.