Hmm.....
But why? Wouldn't a prerequisite system be more interesting? It'd still force you to guide your civ in a particular way in order to obtain the building (get X Great Works to unlock the Great Library, Have a standing army of X to unlock the Statue of Zeus). It'd also eliminate the "OMG, this is not at all what I wanted" while still obtaining much the same thing gamplaywise.
Is there anything you're trying to achieve with this system in particular?
But why? Wouldn't a prerequisite system be more interesting? It'd still force you to guide your civ in a particular way in order to obtain the building (get X Great Works to unlock the Great Library, Have a standing army of X to unlock the Statue of Zeus). It'd also eliminate the "OMG, this is not at all what I wanted" while still obtaining much the same thing gamplaywise.
Is there anything you're trying to achieve with this system in particular?
For the purposes of this discussion you probably should lay how wonders would probably work then. Otherwise it's almost impossible to understand the potential effects on balance. One thing we still know is that Wonders remain an active investment, given that you'd still have to pour in production.
by 20% while they are in that city. The incorporation of all of these factors should determine what wonder you eventually receive. Although this method will, of course, give you wonders that reinforce your existing bias as a civilization, it does give a chance of changing course, and through the use of dummy buildings to provide basic elements 
c5food:, 
, 
, 
, 
, 
, etc.) the new system can cater to the need for predictability while at the same time not compromising replay value. Wonders themselves will provide unique bonuses (+1 
for each ship, for example) and maybe even some benefits on their own, but the bulk of yields from wonders will come from the dummy buildings. Unique every time, the wonder system in Civilization V will never grow old and will challenge the human player to produce new strategies every time.
