Hmm I'm gonna say it'll probably be an entirely new grip. Perhaps the 8fps will only be achievable with a battery grip? So the camera might only be something like 5fps.
I doubt this new camera will steal the D700's thunder though. It's still "just" a DX camera :^) If this camera is as good as we think, that just means the D300 and D700 replacements are going to be even better! Unless of course this camera is replacing both the D90 and D300.
Most probably a new grip. Probably old battery, or updated one, like the D3000 or D60 with the D40's battery.
You know, I do think the D90 replacement will be quite awesome. I mean, as nice as the D700 replacement would be for obvious reasons, it's not relatively attainable. The D90 and its replacement most certainly is.
I'll probably get one. Been rockin' the D40 for a few years now and want to upgrade within DX. Probably won't buy another body for quite some time (4+ years?), so I do want to get the "latest and greatest". If I were planning on a FX body in the future I may have just bought the current D90, or wait for the D700 drop (if ever). I won't buy the D90R until it's been tested though... no preorders from me!
D90R plus a variety of lenses is, to me and my budget, greater than a D700 and 1 lens.
Lenses like crazy for me, I'm going to use my D40 until it plumb wears out and turns into a nice paperweight. Then I'll buy the D90 replacement replacement! :D
So if the rumoured specifications is a D90 replacement.. Hands up.. who is getting one.. ? and who is not getting one. And finally .. who is still undecided.
Nope. Lenses for me.