It'll start at $4199, and in less than 6 months it'll be at $3499.Right now a 5D3 lists at $3,100 (and sells at B and H for $2,800) so the new camera will have to sell for a premium over that.
While tpatana's educated estimate seems reasonable, if I were Canon I'd want to sell at least 100,000 of these in the first year (just to break even on development costs) and would set the price under $4k. At $5k - I can't imagine them jumping off the shelves; particularly since magazine and newspapers are firing photographers (Sports Illustrated just fired all their photographers !).
You're right, I'm thinking of sale prices. I bought my 5D3 about 2 years ago, basically for $2450 after I sold the kit lens. So official announcement price at $4499, and later this year it'll be $3799.