I will add my "speculation"
Only the marketing department of NcSoft knows the answer, but I can assure you COV will not be free.
Does COH cost 15 bucks? Yes
Will COV cost 15 bucks? Yes
Does it cost 30 bucks to play both...probably not.
More than likely they will have a package deal as a bargain for playing both. They just have to figure out what the customers are willing to pay.
Cudac