I really don't think Luigi's Mansion is the type of title you can build your holiday lineup around. It's not the BIG one, it's the one BEFORE the BIG one - If that makes sense. Like it was back in 2019 when it released on Halloween in 2019, just 2 weeks before the BIG one of that year - Sword/Shield. It's not outside the realm of possibility at all to have a similar scenario where Luigi's Mansion 4 is the October title and the new 3D Mario is the November or December title; Although, I'd bet that Splatoon Raiders is going to be that "one before the BIG one" title this year.

Given how much time it's been and the fact that, as @firebust03, most of the Mario Odyssey team is absent from DK Bananza's credits. And it's very possible that once that game finished, they immediately jumped onboard the next 3D Mario game's development to help finish that game. 

And with Pokemon Winds/Waves now slated for 2027, I really don't see how that BIG one could be anything BUT 3D Mario unless, as I said, it's Smash Bros.

Ah, so it seems it wasn’t even a rumor— EDP 8 did in fact split. This is confirmed.

It only makes sense in Brasil

Mario atrás do armário é um clássico aqui, mas o pessoal deve ta boiando mesmo kkkk

Good to know, it's actually surprising they didn't have a new 3D Mario yet, later this year Odyssey will be 9 years old.

If the team is the same, or at least a good part of it, depending on when it happened it can indeed be close to release. If the split was anywhere from 2021 or earlier a new game releasing this year is very much a possibility.