I remember a thread a few weeks ago about the new Mario Party game launching in October with COD Black Ops 4 and Red Dead Redemption 2. At the time i thought Bo4 and Red Dead won't have a big impact on Mario Party sales but with this info I think there's a chance Mario Party could flop. This would also explain why Wolfenstein 2 flopped last year because it launched the same day as Mario Odyssey.
It's not only about platforms, but what you want to do with the games.
There is no interest whatsoever in buying a mario party game if you don't intend to play some local couch coop.
To my knowledge (?) that's not something that either of the other games offer, to begin with.
I don't think there would be any significant impact from this overlap, due to the products catering towards fundamentally different demand that a customer may have.
Bet with PeH:
I win if Arms sells over 700 000 units worldwide by the end of 2017.
Bet with WagnerPaiva:
I win if Emmanuel Macron wins the french presidential election May 7th 2017.