The fact that a big part of this game will be rendered in polygons is not going to take up alot of space, since the coordinates (or what you might call them) takes up very little space in terms of data (its like a 3d text document if you know what i mean :wacko:

)... The main issue will be the amount of images shields and textures, and the quality of these, adn also as said before sounds and music.
For example if you take a ps2 game and play it in high res (could be a port to pc), you will notice that the textures are more muddy compared to average pc games, which is due toe lack of memory ressources compared to pc... ofcourse this is not the case with the new(xbox360etc.)/next(ps3) generation of consoles, since much off these issues has been solved do to the vastly improved memory capacity of these., which truly enables HD gaming on consoles with high res textures...
My bet would be about 1gb for eu3 aswell though...