Kart Player 2008 said:
I theorize that there will be no more unlockable characters in this installment and have 2 reasons for that:
Usually, Unlockable Characters were kept secret and many characters that used to be secret unlockables were revealed early this time.
Custom moves create a lot of unlockable content already and if the entire roster is available from the start this time, people could start focusing on unlocking custom moves right away.
Well, we should note that lately Nintendo has been not that secretive about revealing new characters.
I mean, we knew the entire roster of Mario Kart 8 a month in advance, and 14 of them were unlockable.
Plus, I'm sure that a lot of the characters left to be revealed will be locked. We only know 37 characters so far. I think that all the 3rd party characters will be unlockable just like last last time. So assuming that the cuts are made on Snake, Ivysaur, and Squirtle, and potentially 2 more newcomers (just giving out numbers), then there will be about 48-50 characters this time around.
So that being said, let's say that the 34 non-3rd party confirmed characters are default. That would leave about 14-16 characters unlockable. This is on par with Brawl, as there were 14 unlockable characters in that game.
Of course, a lot of the characters are major and interesting characters, and probably showed them off to advertise. That means that characters like Robin, Greninja, Palutena will be unlockable. Let's also not forget that there are two versions of the game, meaning that some characters that are default on one game will be unlockable on the other and vise versa. So that could mean that Rosalina and Little Mac is default on the 3DS version, but unlockable on the Wii U version.
I highly doubt though that Sakurai wouldn't have some unlockable characters, especially since it would be unorthodox in comparison to the previous installments where unlockable characters serves as a reward for playing the game.