I didnt notice the 2008 Worlds. I dont think Kostner would have beaten either a clean Kim or clean Asada that year, even going clean herself. She wasnt yet seen as a skater at their level. So I would pick Kim gold, Asada silver, kostner bronze for that year.
I agree the 2011 Worlds would have gone Kim, Kostner, and Asada even had all gone cleanly (and really well) though, although this case it would be extremely close.
A clean Asada would still have a flutz deduction and -GOE on that jump btw. She is not capable of doing it any differently.