I'd prefer multiple hosts this time around.
Having just one host is fine if the game is mostly the same each board, but they're not all really the same here, right?
Yellow Toad looks to be the host of the Grasslands board if this is the case, and hopefully, Rosalina will be the host of the Space board then (because I'd rather have her saying something instead of just a cameo at the end)
For other boards, Toadsworth could be a good one, just for which board, I'm not sure.
Also, if there are going to be multiple hosts, I think Nintendo would rather make DK one as well since all he's doing is aiding the other players now.
...I won't be too happy if there's only 1 host, though. That just shows un-creativity on Nintendo's behalf.