The trouble is, what are they going to do?
The first thing that pops into my mind is to update the map itself, but that's a lot of work for potentially a low payoff. People could come back to dominion if it got a shiny, new map, but they might not. Or they might show up for a few games and then leave again.
They could invent a few neat items to spice things up, but that only worked for BMB for a few days.
being the exception, imagine the fun you could have with that in the dominion map. Using gold to upgrade your dominion minions like BMB might be something worth looking into though.
They could fix some champions for the map, like giving
a passive or letting
have something like his dragon, but that would only improve gameplay for those specific champions.
I suppose they could "bribe" players with higher IP gains, but that would just mean more bots.
A ranked mode wouldn't be worth it now, considering a draft game takes around ten minutes to find people for as it is. If ranked brought in more players, great. If not, you could end up waiting longer in queue than actually playing a match. Not good.
Perhaps some dominion-only awards like banners or emblems or boarders? Again, bot bait.
At this point, the only thing I can think of is Riot giving dominion some rubs. Just like we have "Watch CLG make this play" and "Learn how SKT jungles" we could have articles like "Watch team X come from behind in this dominion match" or "See how Y changes the meta of dominion". Let dominion be recognized somewhere outside of the bottom of the patch notes. Have Riot treat it as, maybe not equal to SR, but certainly something better than "Oh, and here's a couple changes for dominion, scroll all the way down to find them".
If there's gonna be hype for dominion, I think it's going to have to start with Riot giving it some attention. But Riot probably won't give it attention until it gets some hype. Vicious.