Uhhh I highly doubt it considering most companies forecast sales, and from that would be able to predict how many people will be online..
Think about it, they've already made $239850720938572, I'm sure they could afford decent enough servers :\
If it happens it happens.
Although Black Ops seems to be packed full of stuff to do via Co op and singleplayer that online play may not be necassary for the first day or two.