Geo: I have to comment, great writing. Did you major in English?

Ok, my 2 cents. I agree with Geo that politics do cause overages with studies and other time delays. However, even if WAAS/RNP and NextGen was put online tomorrow. It would take years before the majority of pilots could use the system. RNP equipment is now just starting to make their way into our fleets. And this still requires op-specs to be written, pilots certified, and LOA's granted. All this takes time.
Even then I do not think this will magically make the congestion over major cities disappear. The problem is convenience. Airlines want to make 5 daily trips from A to B in an RJ, rather than 3 in a larger airframe.