Actually, there are high elo dominion-only streamers. TheFeedski streams on twitch.tv and Nekrogen streams on own3d.tv. I occasionally watch both myself, but you have your pick if you prefer one website over the other. There might be other dominion-only streamers, but I don't know them.
I agree with you though, that Riot needs to start doing something for dominion, and fast, before it completely dies out as a game mode, save for a (relatively) few diehard fans who truly enjoy the gamemode (whether this is immediately releasing ranked or not, that is something for Riot to decide).