Pardon me krew, but I really don't see what the 2018 model year RX has to do with this new colour option. The Japanese Domestic Market does not officially go by model years in the format that the U.S. and some other Western Hemisphere nations do. I read the Japanese article and nothing really refers to 2018 for some reason nor introduction plans for during the 2017 calendar year.
I think this more so concerns the 2nd year JDM changes, that will parallel the North American market RX, designated as MY2017, not MY2018.