The source of the below image is talked about here.
(although I’m utterly uninterested in theorizing/predicting who the Eighth is, some fans may be curious about this editorial piece)
In chapter 43 (volume 6), three of the six Geniuses disagreed with Master Water Mirror that there were only two warlords (Cao Cao and Sun Jian) worth serving.
theory 1: Suppose The Eighth is among those three who disagreed with their teacher, then he is most likely one of the top advisers for the future Shu Kingdom.
(top bar chart, names from left to right)
Xu Shu, Fa Zheng, Ma Liang, Ma Su, Liu Ba, Jiang Wei, Wei Yan, Huang Yue Ying, Li Yan, other
theory 2: Suppose The Eighth is among those three who agreed with their teacher, then he could be for either Cao Cao or the Sun clan.
(bottom bar chart, names from left to right)
Lu Xun, Lu Su, Gu Yong, Kan Ze, Hua Xin, Zhong Yao, Yang Xiu, Jiang Gan, Liu Fu, other
(this data may not be as up-to-date as possible, but it’s not that important either way. :P)