Cheers. We may disagree about their being many must-haves, but I can definitely concur that BOTW is the best game on the system, to the point where if you're going to get a Switch, even in 2019, you may as well get BOTW. (Unless you're one of those folks like me who got the Wii U version haha)
I would say though that the number of must-haves looks set to climb significantly in the coming months though with the arrival of games like Luigi's Mansion 3, Pokemon Sword/Shield, DQ11, (In Japan at least) Animal Crossing, etc. Who knows, maybe even Astral Chain will manage to carve out a rep for itself a cult classic must-have.
That would be great for Nintendo and Platinum Games. It would kinda like being the Nier: Automata for the Switch, which is ironic since Taura, the director of Astral Chain, was the lead game designer of Nier: Automata.