4 player local 8 player online https://www.youtube.com/watch?v=D8bomH0wKfg
I think he was curious if in local multiplayer, each player can play with a single Joy-Con.
I can't imagine this being playable with just one Joycon, given how much you need camera control and extra buttons.
I'm of the same mind that it would be very difficult, but in my opinion, it doesn't have to be optimal or even good; merely operable. Something like:
L-stick - movement
L-click - crouch
A/B/X/Y - camera
SR - break blocks
SL - place blocks
+/- - crafting/inventory (this is where they'd have to get crafty with new menu interfaces/options)
Joy-Con upward flick - Jump (maybe instead use auto-jump like Pocket Edition)