Youve obviously never played previous GT titles to realise a Prologue is always released (well from 3 on wards). If you look at the texture models of the cars in GT5p, you can see why it takes so long. You have to have actually played it though.
but why is it taking another 2 years to finish
i doubt it takes that long to do some textures and car models
how much staff do they have?
part time mod groups on pc games deliver content quicker lol