Except that Sakurai counts each playable character individually, regardless of whether it's a form or not.
By his word, there are 39 characters in Brawl.
My GUESS is that we will have 49 characters in Smash Wiiu in Sakurai's mind but 45 actual spots on the character select screen because of 1.sheik 2.zero suit samus AND 3.charizard 4. ivysaur 5. squirtle. all counted as separate characters. possibly a 46/47th spot(s) on the character select page for Mii or/and the Random icon, mattering to how they incorporate Mii's if they are on the roster (for instance if I simplly choose a characters moveset for my Mii to use it might not count as a "newcomer" spot and just be an interesting feature in the game).
I base this on the fact that the site has the character icons in sets of 9 and the mobile site has 5 at a time, likely this will fit 45 character slots by the end.
However, that's me being optimistic...and sadly after brawl it's tough to get my hopes up even for that highly reasonable amount of characters SO it could also happen that we get a 45 character Roster in Sakurai's mind with 4 of those spots being the sheik/zero suit samus characters and each of pkmn trainers pokemon getting their own separate spot and a character select screen with only 40 different spots.
it's also possible that pkmn trainer will have one spot on the main site and zero suit and sheik will have their own spots like last time.and then in Sakurai's mind we will have 47 different move sets or "characters in sakurais mind" with a 43 character spot select screen, again possiblly 45 spots adding Mii and random mattering to how and if Mii's are incorporated and if they will be a "newcomer" or simply a feature on the select screen similar to the random button.
this hurts my head to think about all this and I'm pushing for the optimistic 45 character icons on the roster with 50 character move sets available and Mii's incorporated in a way that doesn't take up a spot.
This would mean a decent amount of "cuts" to get even the same number of "newcomers" as we got in brawl this time around to fit in the roster, I'd love for them to cut the clone or "similar enough" clone characters (besides cases like ganondorf who should get his own moveset now) and make the clones alternate costumes of the original non-clone character but actually give them a name switch and different voice work and a complete set of color costume changes (similar to wario and his wario ware costume actually being twice as many costumes): ness can have a lucas costume mario can have dr. mario fox can have falco peach can have daisy etc... if this was incorporated it would require no time making new movesets but simplly "drawing" new skins onto existing movesets and adding some voice work (or even make them silent in those costumes who cares) and incorporating the characters we've come to enjoy playing as while still freeing up space on the roster for many Newcomers. Sadly Sakurai doesn't seem like the type to do this and we'll end up with something stupid and pointless like wario being chosen to have an extra number of costumes in brawl. oh well, it's a thought that could really fix this limited roster problem.