6v6v6 is just not the same as 4v4v4. To be fair, nobody has tried it yet (I doubt there are enough people on the PTS to try it out), but just on first blush, that's a whole ball group, and I'm not sure if that is the same experience from 4v4v4s that people have been pining for.
In addition to that, I think loads of people who have played both 4v4v4 and the 4v4 that replaced it are in agreement that 4v4s are just not fun in general. I feel like the reintroduction of 3-team BGs could be way simpler and better by just replacing 4v4s with 4v4v4 without touching the 8v8s.
Best Argonian NA and I will fight anyone for it
20 Argonians
7x IR, 7x GH, 8x TTT, 5x GS, 7x DB, 2x PB, 4x SBS, 1x MM, 1x US, 2x CB, 1x Unchained