I feel it's just a matter of time. I've asked some of my friends about splatoon and while they like it, some don't consider it a day 1 buy since they stll don't know exactly what they can do.
So in a way, it's up to us to host tournaments, generate content, and overall make splatoon as attractive as possible to newcomers so eventually we'll have a really wonderous community that can rake in newbies with ease.
And as some already said, don't act like the Smash (read: Melee) community, though that would take a LOT of effort anyways.