This is my first post on this forum in probably 5 or 6 years. How time flies.
Anywho... I, for one, am excited and curious about the 6D. I have my rusty, trusty 5D (the original) and I imagine that sooner or later I'll be wanting to upgrade. I have a solid investment in Canon lenses, so the Nikon camp is out of reach for me (although the D700 is probably about as close as I've ever seen to a 'dream camera' for me).
All that being said, the 6D strikes me as the spiritual successor of the 5D in some ways. I'd love to own a 5DIII, but I simply can't justify $3500 on a new body at this point or anytime in the near to mid future. The 6D opens up an upgrade path to a new (modern) sensor, improved AF (from my current 5D), and all sorts of other niceties (dust shaking sensor, live view, etc. I know, how very 2007...) that my 5D lacks.
$2100 USD is still a good chunk of money for me but much more manageable that the 5DIII.
At the end of the day... we all live in exciting times my friends. Too many new cameras to drool over and not enough time to shoot!