I think there are some misunderstandings in this thread. The OP is asking if CiV will require Steam in order to run. Empire: Total War required Steam to run, regardless of whether you bought a boxed version or a digital version. Essentially it used Steam as its DRM and patch-delivery service for all versions of the game.
Personally I love Steam, and I buy as many of my games there as I can. This is because it's almost always the cheapest way to get a game in Australia. It's also very convenient - I can switch between all the different games I want to play seamlessly, without having to switch DVDs all the time.
As for CiV, there will almost certainly be a boxed version, and there is going to be a Steam version, too. It's possible the boxed version will require Steam, clearly Firaxis have some kind of arrangement with Valve given that it's already up on Steam.
I do think DD is the future. It's just a more efficient and convenient way to get games from the developper to the player. Just look at some of the indy games up on Steam right now, Torchlight, Osmos, Gratuitous Space Battles etc. DD doesn't nescessarily imply restrictive DRM, either, just look at Good Old Games. It's also better for the environment.
Steam has offline mode now, anyway. And you don't have to worry about losing or damaging your game disks. So many reasons to love Steam.