Personally, I would consider keeping it to three. However, do not take it that only 4 people will join the most populous factions. Remember that there are all those people who voted for factions that won't make it, and thus each of the 4 factions will get more people than just those voting for it. If we start with ~20-25 people, even if a third leave, we still have ~5 per faction. And the Hive only needs one to run. I think it will be fine. And if it isn't, just start an SMAX regular game instead (on Transcend this time).