I don't get why everybody think there will be 4 character per color (per side) as in Awakenings.
Looking at mere numbers I guess:
160 cards is due to 174 (Awakenings) - 14 (Starter only cards/dice) = 160
I think that there will be a slight reduced number of rares/legendaries:
67 cards with die in Awakenings - 7 Starter cards with die: 60 rare + legendaries
(maybe 45 rares / 15 legendaries or something along that line).
My main guess is that Spirit of the Rebellion will feature only three characters per color (per side).
Numbers on the spoiled cards seems to point to that direction actually: Jyn, for example, is a Yellow Hero character with #44 while in Awakenings the first Yellow Hero Character (Finn) is #45.
Even if Jyn was the first Yellow Hero Character (I think she is the last one) there will be one less neutral card at least within the rares.
Furthermore, I guess they will leave more characters on the biggest set of the year.
Following this thoughts at the end of each cycle (3 expansions) we will get 10 new characters per color (per side)
Except Lukas has said that there will be 24characters per expansion in the panel at the pre-release. The difference in Jyn to Finn can be accounted for by the removal of the starter only non-character card F11-D Rifle.
Furelli