Update []: As detailed on the official Asian site for Sonic x Shadow Generations, it seems that Sega will not be offering current owners a way to upgrade to the Nintendo Switch 2 release when it launches on 5th June, 2025.
The information reads: "The Nintendo Switch™ version cannot be upgraded to the Nintendo Switch™ 2 version. (The same applies to DLC.)"
However, you will be able to transfer your save data from the original Switch version to the Switch 2 version. Sega has also confirmed that the game will come in at roughly 24GB, with a physical edition consisting of the controversial Game-Key Card, meaning you'll need to download the game either way.

We've reached out to Sega to clarify whether the above information also applies to the Western release.
Original Story: Sega has already confirmed that Sonic x Shadow Generations will be heading to the Switch 2, but now we have a date: 5th June, 2025. Yes, the Switch 2 launch date.
This means that Sonic X Shadow Generations will be joining Yakuza 0 Director's Cut and Puyo Puyo Tetris 2S on day one, making Sega one of the most staunch early supporters of the Nintendo Switch 2. The publisher will also release RAIDOU Remastered: The Mystery of the Soulless Army on 19th June 2025, and Two Point Museum at a later date.
Not much information on Sonic X Shadow Generations for the Switch 2 has been provided at the time of writing, but players can expect "enhanced graphics" for the new console. We'd also expect a nice little bump in frame rate, but we'll have to wait and see.
Sonic X Shadows originally launched on 25th October 2024 and was met with critical acclaim from yours truly. We said it represented "a monumental return to form for both hedgehogs" in our review, and awarded it a score of 9/10. Frankly, we can't wait to check it out on the Switch 2 come launch day.