I think everyone is jumping the gun a little bit on this 8 player zombie mode.
First of all, it has not been ‘confirmed’ that there will be an 8 player zombie mode.
And secondly, IF there is, we can not assume that it will just be the zombie mode that we have been playing up until now. I’m sure IF there is an 8 player zombie mode, Treyarch have thought outside the square and would release something that actually plays well, not just cramming 8 people into a regular zombie map and hoping people will enjoy it. It would be ridiculous to think that Treyarch would do this, purely because they now have the ability to add another 4 players on there.
I think we all need to get a bit more information before we can make an informed decision if 8 players would be beneficial or not.