Personally I hope that since twisted treeline is almost done, just maybe dominion will finally start getting some love. And though I think they will maybe work on balance issues a bit before they release it, it might hopefully come out some time next season.
The real reason I want to see ranked is so people take dominion more seriously and maybe we get some more regulars.
At the same time though part of what I like about dominion is the care free aspect to it, not nearly as much pressure on winning or losing which I think just puts emphasis on how fun it is.
That is honestly why I would like to see a ranked dominion, I like the random queing and having fun but I would also like to be able to take it seriously which hopefully adding ranked would do.