All the way back in June, it was announced that Forza Horizon 4 would be getting delisted on the Xbox Store beginning December 15th, and unfortunately we'd been expecting it for a while - it always happens with Forza games!
Why? Well, there are licensing deals attached to these titles (think of all the car manufacturers involved), and speaking to Game File recently, Xbox boss Phil Spencer alluded to Forza Horizon 4's delisting as being a situation he specifically likes to avoid. As a result, he's always "very careful" when making deals for licensed games.
"We’ve seen it in racing games that have to get delisted, because you lose certain licenses."
"So I'm always very careful, if we're going to take on a license, that we're doing it for creative reasons, [that] the team has a goal around what they want to do.”
Spencer was talking specifically about stuff like Indiana Jones and the Great Circle and Marvel's Blade during this discussion, where he advised that Bethesda's love for Indiana Jones was the catalyst for that game being created.
But also, he says he's a "big fan of us using the IP that we haven't even revisited", which obviously removes the need for licenses and makes things less awkward in the process. So, how about that Banjo-Threeie, Phil?
As for Forza specifically though, this is a situation that we can't see being resolved in the future - not unless the franchise changes significantly to avoid licensing "complexities", as Phil describes it. The good news is that you can buy Forza Horizon 4 at a huge discount during the Xbox Black Friday Sale - so do it while you can before it disappears!