ChronoBound, this really depends on whether I am satisfied with Smash 4's final roster, the overall selection of new stages and new items, the modes and the gameplay, but mostly it is about the final roster. I am tired of arguing with people online, defending my opinions about who should be added, and always ending up disappointed when certain characters I have been requesting for well over 10 years aren't made playable.
By the time Smash 4 comes out I will be over 30, I just don't have the same enthusiasm for video games these days like I used to have when Melee first came out. I mean, most of my 3DS library are Virtual Console games (nostalgia).
Smash 4 is pretty much the only video game I am geninuely interested in and this is mainly due to nostalgia and Nintendo's history. That's why I support Duck Hunt Dog, Little Mac, King Hippo, Palutena, Medusa, Ridley, Dixie Kong and Kiddy Kong (team), King K. Rool, Toad, Meowth (or Team Rocket), Mewtwo, Impa and Tingle.
I grew up with these characters throughout my K-12 years. I was already familiar with Mario, Donkey Kong, Zelda, Metroid, Kid Icarus, Duck Hunt, Punch-Out!!, R.O.B., Kirby, and Pokemon long before I played Super Smash Bros. and long before I first discovered the Internet. That's why I'm always pushing for these characters to be playable characters in Smash 4.