Switch on Ranked Dominion during the preseason
Consider it an experiment.
If there's no play to speak of, then just shut it down against once Season 6 starts. Take Draft Queue along with it. I won't hold it against you.
But if it suddenly revives the mode due to people streaming back to try out the new competitive mode on a competitive map and investing the effort needed to learn to play it well because suddenly it means something?
Wouldn't that be a good thing?