I think people are underestimating Zelda. It doesn't have to be as a well known as Mario, it is still very well known by almost anyone born post 1980.
Lets not forget BOTW outsold Super Mario Odyssey by a large margin too ... Zelda has a multi-generational fanbase by now because it has been a thing since the 80s.
I remember even working in retail in the late 90s and a grandmother coming in to buy a Zelda DX on Game Boy Color and saying she knew the brand because she had taught her grand daughter how to read using the game and the instruction manual. Zelda may not make a billion right out of the gate, but I could definitely see 750 million+ and then subsequent sequel Zelda films having 1+ billion potential.
Much like not everyone knew Iron Man and Guardians of the Galaxy at one point were a C-tier Marvel IP.