Well, I'm almost sold.

No hardware keyboard. Honestly, I can take it or leave it. I use both hardware and software keyboards on my N900.
No removeable battery? Never owned a spare for any phone I've ever had, so it's not an issue.
I don't use the video out on the N900 so the lack of HDMI on the N9 won't be an issue. It still has video out, though.
I've always found the FM transmitter to be problematic in my car and prefer to use the AUX input on my in-car stereo. So the lack of a transmitter won't be an issue either.
Lack of in-browser flash is disappointing, but it's not the end of the world and HTML5 is gaining ground all the time.
64gb and out of the box FLAC support are most welcome, an 8MP camera is a bonus as is the bigger, harder screen, and the UI looks the part as does the handset itself.
I'll be keeping my N900, though, as I like to use it as a mobile linux PC.
I won't buy an iPhone (not keen on Apple) and as for Android with all it's bells and whistles, well, I like to be different.
It will be a straight fight between the WebOS Palm Pre3 and the Meego-Harmattan N9 for my next phone.

Unless, of course, somebody announces a true successor to the N900...