While Ubisoft hasn't made it official as of yet, it appears that Rayman Legends: Definitive Edition will be out on Nintendo Switch on September 12.
If you go to the Coming Soon tab on the UK eShop, you'll see all the forthcoming software that will be available on Nintendo Switch in the coming months. Well, smacked right in the middle between Pokken Tournament DX and Mario + Rabbids: Kingdom Battle is Rayman Legends: Definitive Edition.
This Switch version will have all the delights the base game had on other consoles back in 2013, as well as a solo and tournament modes for the excellent Kung Foot mini game.
Rayman Legends: Definitive Edition will be available on Nintendo Switch from September 12 (apparently).