Radiator Springs Racers is the 21st century version of Pirates of the Caribbean; one of those mega-E Tickets that people gush about to the folks back home "You won't believe this new ride they've got!"
Wrap up that excellent ride in an amazing environment like Cars Land, and I think it's only local (and delusional) SoCal fans who want to keep that all to themselves. It's inevitable that it will be cloned for other parks around the world, just like Pirates and Space and Thunder and Midway Mania and Star Tours and Splash and Mansion and Small World and Soarin' and Jungle Cruise and Tower of Terror, etc.
As for Tokyo's Rivers of America, I never thought it worked very well. It is so perfectly maintained and overly manicured, like a stereotypical Japanese garden, that a ride on their Mark Twain comes off as being sterile and very fake. The unfortunate
1970's Corporate Theme Park vibe is at its strongest in Tokyo on their Rivers of America. I love me some Tokyo time, but I won't miss their obviously fake reproduction of the Rivers of America for one minute.
Now, what might this all mean for WDW's Rivers of America? Or for Cars Land East in WDW?