It would be hard to monkey with the concept of Cars Land and still have it work in the way it does at DCA. The total recreation of a town and the majesty of the rock cliffs creates a level of immersion that doesn't exist anywhere else but at DisneySEA. I hear the new Fantasy Forest in Orlando is going for the same type of immersion. This represents a change for the Walt Disney Company.
That may be one reason why, if the rumors are true, it appeals to the OLC. Total immersion in an alien environment. Except for Luigi's, the rides are great. And if OLC built Luigi's, the ride vehicles will have been completely redesigned. I think we'd see a surface area at least twice as large as the one in Anaheim, and single-person ride vehicles so they're much more buoyant.
As far as cloning goes, the amount of people who go to Tokyo Disneyland and also to a park in the US is a pretty small number, not something OLC is concerned about (or they wouldn't be cloning Star Wars 3D or Toy Story Mania). In fact, cloning within the US doesn't seem to bother most people: usually folks go to either Orlando or Anaheim, but the number of people who regularly visit both resorts is not enormous.