I'm not sure I buy that logic. Quantity of games doesn't necessarily correlate to the people showing up. Smash bros is a bit different. We haven't had a smash bros since (early) 2008, whereas we had DKCR in (late) 2010, Mario U in 2012 (or 3d land in 2011), Mario Kart 7 in 2011, and Wind waker HD was just a remake of a game anyone could play at any time. I'd also argue that smash bros fans are a bit more fanatic (we're on OT 8, here) and are willing to jump through more hoops to play the game.
While I am imposing my own feelings, I know i'm not alone with those feelings. I know a lot of people who love smash bros so much that they'd be willing to drive over an hour (or more) to go play it, whereas they wouldn't care to do so with a game like Mario Kart or Mario 3D World.
I'm also sure a lot of the people who already went last year will also go this year (just because they are big nintendo fans). Add that number to the smash bros fanatics, and i'm pretty sure the turnout will be larger. Just a gut feeling, but I think I'm right.