Almost There Games recently created an unofficial PC port of Forza Horizon 2 for Xbox One. Discussing future work, the developer expressed interest in porting Forza Motorsport 5, Forza Motorsport 6, and Halo 5: Guardians.
This intention was revealed in the developer's response to a user's question.These three titles are among the few remaining exclusives on the Xbox One platform. However, there is no specific release date yet.