I would guess that CA will limit the tech tree to advances that are actually significant; I very much doubt they want to make it too complicated and full of "fluffy" stuff. For one thing, larger tech trees can be intimidating to new players. For another, they don't want to create a tech tree so huge and/or varied that the AI can't handle it -- the simpler it is, the better the AI will be able to use it. Thus, I would say there'll be fewer, more important techs as opposed to many, only semi-useful techs.