When Mclaren introduced the 650s, they made it crystal clear that switching to a P1 like front design will provide a 30% increase for aero efficiancy. From that point it was also clear that a replacement from the 12C GT3 to a 650s GT3 was incoming.
Weither or not this change of front styling was solaly design for a better GT3 package and then applyed to a road car will be a lucky guess. Mostly it's a nice reminder of what those car company used to be. Their sole purpose 50 years ago was not how many road car they could sell, but how many wins they could get from various championship.
Road car were just a legal step you had to pass in order to homologate your race car. That, brought legendary names like GTO and GT1.
From today's car company, Mclaren seams so far like the one with the closest and cleanest bound from tracks to roads.
Will they one day, create first a GT3 car and then civilized it for homolagation purpose seams unlikly, but at least the 650s GT3 looks like something else.