I think it would be awesome to have 16vs16, but I don't see that happening soon. Plush they would have to make the WZs maps bigger.
I could see that happening, but also imagine, in a 12v12, needing to keep 2-3 defending while a massive brawl, 9v9 happens at mid (CW, NC or HG). Huttball would/could be insane with the same size map. Larger teams could allow for some wicked ambushes, say 6-8 stealthies.