Queue Size Display
I think this is a small change with potentially big benefits. Somewhere on the menu screen or maybe tucked away in the corner of the main screen there could be: A queue size box that shows the current queue size for 1v1, 3v3, and Downfall. Anyone who wants to play one of these will be more likely to search for a match if they know other people are searching at the same time. And people will be more likely to search if they know others can see that they are searching. A simple idea like this could potentially bring 3v3 combat back to life.