That's what I guess (and hope), too.
But there are so many rumors and clues that I would not rule it out completety.
At first I was: "New engine, YEAH, new chances for a better game!"
Now I am: "PLEASE keep EGO and just fix those myriad of bugs and other annoyances in this game".
I think the idea came up because they switched to UE4 on WRC. But the reason was simply because EGO could not handle those huge stages in rally anymore.
That reason makes no sense in an F1 game with fixed tracks.
The only reason of using UE4 in F1 24 would be that they plan to switch to UE5 in the future and this is the first iteration. In this case it could make sense to first use UE4 and not go to UE5 directly as they currenlty have the knowledge at hand in form of the guys that code WRC.
Of course: only speculation ....
My guess: they keep EGO
My fear: they use UE4 and mess it up BIG TIME......