Yes you will definitely need more RAM , at 75% of the largest map cleared, my Ram usage was at a constant 5.4g out of my 6g and would spike often making it almost unplayable. I went and got 2 8gb sticks and it runs flawlessly now at 16g.
I really hope we wont need more than 24g, (hopefully only 16) of RAM for the final largest map.
With all 100 opponents on the largest map, I have a feeling it may end up being that way. If the final map is 4 times as big as the current largest one and if 8gb is good enough to play this size then 8x4=24, (+100 AI opponents),, I guess will see how well the big optimization goes before release.
This would be a good question for the live stream next week so some of us can prep up. I already spent 150+ cash to upgrade so I could continue my immense map. Sad thing is my x58 will only handle 24g RAM max as far as I know.