I'm not sure about them running out of good material for updates. There are loads of things they could do:
-Characters: Captain Falcon, Animal Crossing character, Nintendo DS logo character, character from symbol #19, Marth, Ness, Mr. Game & Watch, Ganondorf, Luigi, Jigglypuff, more...
-Special moves: any of the above, plus (if any of these characters have new movesets that we'd want to see) Kirby, Pikachu, Samus, Zelda, Bowser, Donkey Kong, Yoshi, Peach, Ice Climbers
-Final smashes: Ice Climbers, King Dedede, Lucas, Snake, Zelda
-Stages: F-Zero, Sonic, symbol #19, new Game & Watch stage
-Music: F-Zero, Ice Climbers, Kirby, Mario, Mother, Nintendo DS logo, Sonic, symbol #19
-Classic controller controls, remote + nunchuk controls
-Second boss of Subspace Emissary
-Assist trophies: Advance Wars, Tails if that one report was accurate, Pokey if that other report was accurate
-They could start showing off normal attacks instead of special attacks
-Alternate costumes update
-Update showing Kirby's hats for several newcomers (especially the newcomers whose neutral B attacks we haven't seen!)
-Full detailed update about saving replays
-Explanation of what coins are used for
-Explanation of that "method for powering yourself up" in Subspace Emissary
-Random gameplay footage--you know you'd love it. >_>
-Comparison shots of Easy and Intense difficulty