I'll go on record... here:
Canon will price it higher than the Nikkor equivalent...
I would not be surprised if the initial price is in the $3500 region....
Hopefully once they have a production surplus, then 2500 might be feasible in a couple of years.
I would expect a similar, if slightly higher, trajectory as the 70-200/2.8IS II. Start at about $2800, settle at $2300 after 18-24 months.
Some people in Japan think so too. About 3000€. rotating zoom. When?? (End 2013/mid 2014??)
But japanese Canonians are discussed about the mentioned rumored pricing. What the hell makes this lens 2-3 times more expensive then the existing predecessor model? There is no better light intensity rumored. The rotating zoom and a better IS will not be worth the money Canon wants for this lens.
But... the big but will be, that you have to "bite the sour apple" (Sorry for this Germanism), because there will be no IS lens that meets this focal lenght.... So another cash-cow will be born.