I'd hardly consider today's update as filler, based merely on the fact that another piece of the sideways-wiimote puzzle was put in place. Pressing 1+2 was definitely not a sure thing when we first learned about the four kinds of control for the game. I agree that the rest is geared towards newcomers, but news on anything that has been speculated about (sideways-wiimote specifically) should be appreciated.
I'm always up for more character reveals, final smashes, and stages too. I'm just saying, people complain when they aren't satisfied with a certain update just because it doesn't include a "juicy" detail, but honestly, these things will come along; you can't always expect mindblowing news every single day.
That's all my point is, though. Nothing to dwell on.
As for my prediction for tomorrow's update, I say that it'll be a stage. Either that or a notice, considering E3 is around the corner (as I said before). Those make sense more than anything else right now.