Also from your post, that's actually not true. What will most likely happen is the zombies will spawn to be the correct speed/strength for the number of people playing. So instead of needing 8 players, you can play with any amount of players and they will most likely generate to fit the number of players.
I've been informed by a really reliable source that zombies are diffenet and it is 8 players, so i am guessing that they will be stronger and faster. Meaning you will need more people.
By very reliable source you say? He wouldn't happen to be the president of Treyarch would he? Cuz I heard the same...