Sakurai would be very dumb not to do something special (at least a character or stage) on December 3rd though. Fan backlash would be amazing.
Problem with all the hardcore fans is that the ultimate end game is going to put money in Nintendo's pocket.
All the *****ing and whining they do will most likely fall on deaf ears because the y know that smash is going to sell regardless of the competitive community (unfortunately).
I don't think a lack of updates or a lack of interesting update would deter anyone from these boards who planned on purchasing the game from buying it.
"I would play Brawl, but that december 3rd update was so terrible, I decided not to" <----------- Not realistic at all.
The problem with being a hardcore fan is that often times those individuals wind up becoming "slaves" to the developers. Developers want to cater to new crowds, especially with a new game, because they know that most of the hardcore players will be with them in the end. The ones that are lost will often times return at a later time anyway.
Its similar to people who ALWAYS vote republican, or ALWAYS vote democrat. The candidates are going to do little to address the issues that effect you the most because they are guaranteed a vote. If a candidate had to persuade a group, and actually back up some promises, they would cater to the group that the candidate would have to work for to get the vote (theoretically).
Personally, I don't think nintendo cares if we get upset for whatever reason, because we are guarenteed money to them.