Amazon.de, the German Amazon retailer website, listed Forza 5 along with multiple photos of the presumed box art.
Although the platform listing indicates an Xbox 360 release, the box art and game reveal from earlier this week clearly points to an Xbox One release.
But most significant about this listing relates back to the Mirror's Edge 2 post from earlier today. Considering that Amazon.de listed both Mirror's Edge 2 and Forza 5 only a few days after the Xbox One reveal event, slightly increases the chances of Mirror's Edge 2 showing up at Microsoft's E3 press conference on June 10th.
During the Xbox One reveal, Don Mattrick explained that the within the first year of release, the Xbox One will see 15 new exclusive games, 8 of which will consist of new intellectual properties.
Counting all of the known or potential games so far, Forza 5, Quantum Break, a Black Tusk developed game, a potential Ubisoft title, a return to a previous Rare franchise and now the possible exclusivity of Mirror's Edge 2 will bring the count for exclusives down to 9 games and 6 new IPs.