Have you considered that the Japanese want US forces there very badly? Local NIMBY attitudes will end up taking a back seat to national strategic priorities and geopolitical reality. A quick review of Chinese military spending may be  instructive.
Based on an understanding of the historical basis of the US presence there, one might say US basing rights were bought and paid for in perpetuity. The Japanese should be happy the US didn't annex Okinawa as the 51st state. 
FWIW Futenma is being moved but there are other local NIMBY issues to be addressed even with that.