I have to say at this point; this years McLaren is very much this years car. It is completely different design to last years and so the potential for improvement should be pretty large. Red Bull have been evolving their design for at least 3 seasons now (and more like 5 really) so i think we're seeing it at it's limit. That being said it is by far the best car in the field but i believe their reign is coming to an end.
You never can tell what Newey has up his sleeve though.
As much as I like McLaren, I have to say I believe the Red Bull is still THE car so far.
You correctly observe the Red Bulls as being evolved, but don't think that this years car is anything but new from the ground up. Obviously the philosophy being the recent cars has been very sound, so why change for change sake? Everyone else has either copied them, or gone out on a flyer to try to catch them. Designing a different looking car, doesn't mean more scope to develop it. After all, the Mclaren really improved after they introduced a new floor and exhaust based on.... the RB7.
If you look back at Newey's career, all his Williams( 91-94, 95-97) and later the Mclarens (97-2005) were all evolutions of the previous years cars.
History shows the most quick cars, from the best design teams are all evolved over time. Other examples besides Adrian Newey are:
1984-87 Mclaren by John Barnard
1987-92 Mclaren by Gordon Murray
1989-91 Ferrari by John Barnard
1991-95 Benetton By Rory Byrne
2000-06 Ferrari by Rory Byrne
2004-06 Renault by Bob Bell/Tim Densham
To me evolution is the sign of a fundamentally sound car. I see this years Renault R31 as a straight development of last years handy R30.
Cheers,
Pat