Online all the time? Yeah ... that's the one thing that will absolutely prevent me from buying the game at all.
First of all, my provider - actually, practically all Canadian ISPs - have instituted bandwidth caps with ridiculous fees for overage. I will not waste bandwidth unnecessarily, on a single player game. Sad, but there it is.
Secondly, I always go offline to play games so that I can shut down my firewall and anti-virus stuff, along with alot of the services and processes needed to be online. This nets me some pretty hefty savings on cpu and memory usage, and really boosts performance - the difference in things like turn times is very noticeable.
So any sort of online DRM and I'm out. Bad reviews etc won't stop me, I'll have to see for myself anyway 'cause it is civ after all, but online DRM is going to not only slow my game down and make it less playable but will also cost me money/bandwidth whenever I play. The big attraction of civ is that I pay a one-time cost and get hundreds, maybe thousands of hours of entertainment out of it. Online DRM would utterly destroy that value scheme, for me at least.