Four of Diamonds.
I'm really curious to see what the producers do. If they put the judges' houses groups to a public vote, which is the obvious solution, it's hard to see how 4D doesn't win. Just look at the poll.
But obviously the goal for the groups category this year was to get 5AM to the top 4 or so (ideally the final) for a commercial launch. The producers could probably ease 4D out in midtable with 3-4 episodes of boring staging/songs and lukewarm treatment, but it's playing with fire as they're likable and pretty decent vocally. Not to mention it removes the option for them to bring 4D back in a year or two, if they see any commercial potential there whatsoever.
I bet they are regretting Louis saying on air that 4D would have been his next choice. Skarl3t would be an easy out if they could engineer them back, as good as their individual vocals can be.