Let's face facts, people like Hotshotgg make jokes and won't touch dominion for one reason. It isn't competitive, there is no outlet for competition, the queue times tend to be very long, and there is no ranked or way to measure skill.
If Riot wants Dominion to ever be something beyond "Fast and Fun" it needs ranked now, not later, not when it's balanced better, just release it. Why can't it wait? Well let's look at TT, for the first couple of months people putzed around with it and even the higher level players cared and wanted to learn it and take part in the tournaments. Over time, however, Riot stopped balancing the map, stopped holding tournaments for it, and overall it got left in the dust as a failed experiment.
While Riot has done a good job at publicizing and keeping interest in Dominion high, their key failure is the obsession with balance the map before giving a ranked version to play. For without a ranked mode, there can be 0 hope that it will ever be taken seriously by anyone but the casual gamers because hardcore gamers need rewards in forms of tournaments and a ladder system to separate them from the rest.
It would greatly be in Riot's best interest to forgo further balance and simply push ranked out as soon as possible. Why? Because the map won't ever become balanced if the only ones that play it are the lower skill ceiling players, for while a good chunk of dominion fans are not "Bad" streamers, LoL celebrities and the like cannot keep their audiences entertained without prospect of seeing Elo/Ladder gains and tournaments.
TLDR: If Ranked is released now it won't be too late for the competitive scene to pick it up and people will give it a shot. If they delay it will be cataloged in the back of the game options with TT. Plus the map needs all skill levels playing it to expose balance issues and ways to fix it.