After being in a lot of fledgling competitive communities, one of the main thing that gets more support for competitive functionality and mechanics is a shown interest. I mean we're showing interest here for sure but I think if they're not already aware of the desire for competitive play then we definitely need to make them aware of it. However definitely don't loose hope, after reading quite a few interviews it seems the guys over on the dev team only planned it to be a more casual game however that doesn't mean they wouldn't be open to a more hardcore fanbase at all as far as I can see, I think it's simply the devs underestimating the reception of their game honestly.
While it's only a console game, the WiiU has a good few years left in it as far I can see and I know of many games that lasted long after they stopped being officially supported. Really it's all down to how determined the community is on the matter. I know of games that have no custom lobbies and random matchmaking that still have tournaments simply because the players are that dedicated.
And hopefully if a Splatoon 2 comes around then a shown interest during the first game may prompt the devs to include more competitive functionality.