However, I think that the Corvette vs Suburban argument might hold even in the face of your logic.

Except when you consider that Chevy's *never* really had a cohesive image amongst its products. I think that's why GM has a lot of other specialty brands (Buick, Saturn, Pontiac) which each tend to have their own particular branding and image. I'm no Porsche historian, but it seems to me they've always done one thing and done it well. Now, even though the car lines won't suffer, the image is indeed dilluted. On the other hand, Corvette always existed amongst other Chevy models, so there was no real image to dillute.