As we've explained here before, the key to Jay Leno's continuance on the air rests with the key affiliates. Their post-primetime newscasts (11 PM in most markets) are a key profit center. The reason that Conan and Dave start at 11:35 instead of 11:30 is to allow these shows to squeeze in another lucrative commercial break.
This article suggests that some NBC affiliates are pretty darned unhappy with the numbers Jay is delivering; that his lead-in is so weak that it's costing them a lot of bucks. The thinking was always that they'd wait to see how new Jay shows would fare against the CSI reruns before they made any changes…but then the thinking was always that Jay wouldn't lose by as wide a margin as is presently the case. It's looking like the network may not be able to keep affiliates on the reservation until such time as the competition is in reruns.