I'll believe that when I see it. I'd guess it will be priced more like $2500-2999. Don't be so quick to drop your D300 - are you in this to have the latest equipment or the best equipment? If you look back to when the D200 came out, the first iterations had severe banding issues and what not.

Just stick with what you've got, your Sigma lenses are DX (ie. not full frame) anyway. You'd be able to use them (assuming the D700 has a crop mode) but why would that be any better than what you're using now?

Just my opinion, but there are always going to be new cameras. Usually when Nikon drops their prices it's because something new is in the works.