Didn’t have a chance to respond in the last thread but welcome to the forum! I think keeping UE5 in their collection of engines is a good idea. According to Epic and what I’ve seen some devs expect is that the transition from UE4 to UE5 to be rather seamless. UE5 is more like UE4 next gen edition…if that makes sense. They didn’t make any major changes like we saw with them replacing the scripting tool from Kismet to blueprint between UE3 and UE4. That was a major change. Technically Epic could get away with calling UE5 UE4.5 but a new number looks better when marketing the engine for “next gen”. Since so many developers at Xbox have so much experience working with UE4, all of that experience should apply and benefit games running on UE5.
On top of that, keeping it as an option would increase efficiency for new hires who may also have experience with UE4 from another studio or schooling. In this scenario it would be easier for a new developer to hit the ground running within a studio than to learn the tools for a proprietary engine.