I want to point everyone here to the Pyra Project:
https://pyra-handheld.com/boards/pages/pyra/

The mobile variant could be close to what we want.

Main similarities to N900:
Awesome Keyboard, Resistive Touch, Open, switchable battery

Main Advantages
Fast processor, lots of RAM, USB host, compass, gaming controls, video out

Main Disadvantages:
Bit bulky, 139 x 87 x 32 mm
Screen not on top in closed state, no phone feeling
No integrated camera
Weight?

If enough users are found, it may even be possible to create a variant of the Pyra?

I dream of a Sailfish device similar to the Pyra, a bit smaller, OLED flip screen like some modern notebooks, and with an 808 Pureview equivalent camera module with complete firmware access and Bless N900 equivalent.