I'll have to see some gameplay and get some idea of what the game will be like mechanically before I can get hyped, but I am very glad to see them stick with BOTW's style. I'm liking the darker vibe too.
2021 release at the earliest though; if there's one thing we've learned about the Zelda team it's that they take their time.
Based on the footage, it looks like it has been in development for a little while already. Looks like a Majora's Mask style sequel, reusing the assets of the first game, which means we could see a much faster development time. Holiday 2021 should be pretty easy for them to accomplish.