When the as-is product is as incredible as TDR is, the pressure for constant expansion and improvement isn't there. The parks are rammed as it is, and people love them.
It's interesting to read that they feel the numbers are stagnating due to demographics. The current Resort cares precious little for attracting overseas visitors, so it'll be worth watching how they play this out if indeed they are taking the Resort on a slightly new path with this as the Japan Times article suggests.