Was thinking the same thing recently...
A couple weeks ago, I flew TZ to LAS from IND (my home airport). While most ATA flights leave from IND concourse C, this flight, on a 757, left out of concourse D. D is the US Airways concourse, when US used to have a mini-hub at IND. Now, it's only about half used. The walk over to D takes you past several empty ticketing couters as well. It really made me stop and think about Indy's construction of a new midfield airport to replace the current one - with so much unused space, and no airline looking to establish new hubs anytime soon, what's the need for a whole new airport?
Last week, on a trip to MCI, I had a couple hours to wait before my NW flight left. I took a stroll through terminal C. More than half of this terminal is empty. I know US Airways used to have a mini-hub at MCI too, and I wondered if this was the terminal they used, although they use A now.
I think this is all evidence of how the negatives of the hub/spoke system are starting to outweigh the positives. I see the trend toward "focus cities" like AA @ RDU, NW @ MKE, IND, and GRR, etc., is the first move toward a dismantling of the hub-and-spoke system in favor of old-style point-to-point routings. It will be driven by the airlines' (or rather, airline investors') need to free up capital and not have it tied up in hub airport facilities.