The next Mario Kart should absolutely be the #1 launch title exclusively for Switch 2. Other than that, I am hopeful that 2D Mario can be held off and launch as a Switch 2 exclusive. I feel like whatever Pokemon title is released the same year as Switch 2 (betting on a Crystal remake for 2024 and Gen 10 for 2025) will be released on both Switch & Switch 2, so I'd consider that a launch title as well. If it's Gen 10, then I could see Gen 10 DLC throughout 2026 being cross-platform as well. If the system launches in 2024 then I could see Gen 10 and up being exclusive to Switch 2.
DLC for 2D Mario & Mario Kart could also help flesh out the Switch 2's first full year afterwards.
I don't see us getting a new 3D Mario or open world Zelda at launch or even a year after launch. That being said, I could see us getting an OoT remake the year after the Switch 2 launches. I also see Smash Bros. & Animal Crossing coming the year after. Maybe we could get Mario Party that year as well.