for sure it'll be expensive, thats about as certain as the sun will rise tomorrow.
Pricing should be comparable to the 300 2.8, and the nikkor 200-400 vr.
I'm not suprised about this lens though, the canon camp's been crying for awhile now that nikon have the 200-400 so it was only a matter of time before canon released one.
For those waiting for the 100-400L replacement, THIS IS IT, well sort-of.
When the 70-300L was released many claimed that it was the 100-400 replacement, except it fell short somewhat.
It did however leave a obvious hole for a 200-400L and voila.