Rashiminos
Fool Prophet
I think that would be a pretty bad call by Firaxis.
Large patches mean content updates. Bug fixes will be small, either in the form of minor patches or fresh binaries - nothing beyond a few megs a pop.
If Firaxis choose to release free content updates, it would be pretty bad if they released it as a required patch. It wouldn't make any sense and this is exactly what the free DLC system would be for.
Time will tell, but I don't think groundless speculation like this helps.
Civ 4 BTS 3.13 to 3.19: 170-something MB. Groundless? No.
http://redwing.hutman.net/~mreed/warriorshtm/fanboy.htm