In simple terms if Toyota are extolling the 'eco-friendly' aspect of a weight saving technology (over extra weight initially introduced to the roof in this case) then they must have serious plans to roll-out to all vehicles whether headliners or other body trim in the not too distant future.
Why? Well they are not going to gain much PR credit / acolades as a 'green' giant from just a couple of models selling an 'eco' % of say max 200,000 per year out of their ~ 9 Mil per year vehicles.
And don't forget even on simple models miles per gallon is a key criteria for some buyers given the cost of fuel, so e.g. if a Toyota can gain through reduced weight even 1 mpg over say a Ford, that could be enough for sales fleets doing vast miles. NXT is now a quantified contributer to that weight saving as defined by Toyota themselves.
I think another couple of Toyota models, with this additional PR spin, and we should start to get momentum from the rest of the industry, and the SP should move strongly up on that basis.