Forza in Early 2022 would be fine since Forza 7 and Horizon 4 are already on Game Pass. Those will be two racing games to play for those buying a Series X|S.
My thinking is Forza 8 in either late 2021 or early 2022 and then Horizon 5 in 2023. I think that comes out after Fable, which I'm putting down for late 2022.
Won bet with t3mporary_126 - I correctly predicted that the Wii U's LTD at the end of 2014 would be closer to 9 million than 10 million. http://gamrconnect.vgchartz.com/post.php?id=6673287