Hyrule Warriors: Age of Calamity launches November 20, 2020.
It sure seems canonical, and it sure seems awesome. Trailer appears to show that the game is heavily story-driven, allowing you to experience the Great Calamity event that preceded the events of Breath of the Wild.
Trailer also appears to show that at the very least, Link, Zelda, Daruk, Revali, Urbosa and Mipha are all playable characters. Hoping for baby Sidon, flower lady and Monk Maz Koshia as additional characters.
I had the pleasure of experiencing BotW for the first time in 2020, and it owned my life for a few months. Age of Calamity announcement was an incredible surprise. And we're still getting a proper sequel!