My understanding is that the upgrade packs are only if you want those performance improvements. There shouldn’t be anything preventing you from playing your old switch games as is, especially with the save data transfers and the backwards-compatible card slot. So the old version should still be playable!

XC is one of a very small number of series that I will still preorder. I never owned a Wii U, so I never got to play this game. I’m so excited!!!