I really want to see the pricing first. If its priced well and a successor to the 3DS and Wii U, then 40 million+ seems more than attainable. However, it needs to attract 3rd part support, or it will fail.
Made a bet with LipeJJ and HylianYoshi that the XB1 will reach 30 million before Wii U reaches 15 million. Loser has to get avatar picked by winner for 6 months (or if I lose, either 6 months avatar control for both Lipe and Hylian, or my patrick avatar comes back forever).