Yea. I don't think you could pull off the standard "rags to riches" type campaign, owing to the lack of metaphorical rags, but that doesn't really prevent a compelling single player campaign. Consider rally of F1 games... in terms of variety they're inherently hosed, but it doesn't cause them all to lack stuff to keep a single player consistently occupied.
As another example, PGR3 imposed a > 170mph limit on itself for car selections, partially due to the move to the 7th gen causing them to have to start everything from scratch. They just built the campaign around that selection.
True. Im just not creative enough to see what they could do. Maybe something like the Pro Race Driver series. Even then Im not sure that would bring any sort of satisfaction to the disappointed fans.