Your "curved approach" idea is essentially a non-event. There are already MANY "curved approaches" published, but they are called DME Arc approaches. They can be flown by ANY airplane equipped with a VOR and DME, and can be flown using VNAV by airplanes so equipped. There is no added value in the Novair idea, because such approaches can be implemented anywhere. RNP requirements simply keep the airplane closer to the lateral path. While that may have some marginal value in perceived noise by some people on the ground in some areas, it is NOT any "greener" than any other approach currently in use. Indeed, the people who developed the traditional approaches could have implemented a DME arc approach if it met the clearance and other safety criteria.
Once more, there is NO DIFFERENCE in the normal vertical profile in the Novair approach and any other straight-in or DME arc approach. Current FMS systems already plan for idle thrust until gear down. The need for "avoiding urbanized areas" was brought on by developers building under airport approach and departure paths, and governments allowing them to do so. Those who live and work in those areas, in general, knew what the situation was and decided to pay less money for more house (or office) under the noise patterns. Many of he responses to their complaints have compromised safety in the past, and we have no idea as to the criteria used in these new "curved approaches" using RNP to ensure an equal OR HIGHER level of safety.
So, again, what is the tradeoff between safety and a "curved approach" to a shortened final approach?
And finally, the net effect of priority schemes will not be "no difference," but an INCREASE in fuel use by all the airplanes delayed by the priority airplanes. Mandating equipment is not a panacea. MOST airliners in service in the US and western Europe today already have the required RNP ability, and ATC still cannot allow them to use their most efficient profiles. Then what happens when ALLL of the airplanes have "priority"? I think we'll be right back where we started...
Someone else pointed out that ground operations may be the place to start finding new "green initiatives." That may be a better approach for you, since you don't appear to grasp the realities of air operations, and tend to fall prey to marketing without considering the side effects...