i agree with you about the other manufacturers, hell i would drive an a segment audi, vw, aston, etc. the european market does not equal the us market.. thats an "average" car over there.. and they don't build their own competition.
when americans think cadillac they think grandpas or escalades.. not small economy performance. anyone interested in the latter would not want the added weight of the caddy components. i doubt they will upgrade and pay for emission certification of a new engine just for the caddy version.. ie if it goes into the caddy it WILL go into everything..
like i said, americans are stupid and accepting. just like the versa, fit etc it will sell because people are brand loyal, when the sentra or civic they bought 5-6 years ago is now a car they cant afford and the versa or fit is in the price range they accept it.. if cadillac builds it someone will buy it.. but it will be another redundant model. (unless they do the caddy awd instead of the buick to kill some of the overlap)
Also the audi a2, aston martin cygnet, vw polo, hell even the smart car, were all designed and produced as luxury performance super sub compacts.. While cadillac in an attempt to compete will use a refaced "bottom of the barrel" daewoo. Dont get me wrong i love my aveo, because i know what it is.. but its still the "cheapest" car in america.