I think OBL will probably martyr himself, and his henchmen will do everything they can to prevent his DNA falling into our hands. Better to have his Holy Name live on as a mystery than have his remains floating in a jar of formaldehyde in an FBI lab.
If he is alive, here is hoping this happens soon.
Some thoughts to explain this:
1. The Bush Admin is trying to dispell the "They already got him on ice somewhere" theorists. They know it is just a matter of time before OBL is confirmed captured or dead anyway, and ginning up the chatter about the pursuit will lend credence to the capture. To not do this will allow the "October Surprise" false scenarios that will then be raised by the McCauliffs of the world to detract from the accomplishment. In fact, I think the false capture rumors are nothing but a scam to innoculate the Dems against the political results of the capture when it comes. They hope to get everyone involved in the capture to try to defend that it really happened how/when they said, much like Bush's National Guard service in Alabama.
2. The other possibility is that raising more awareness of the hunt is part of the plan to pressure OBL's gang into making some mistakes--perhaps flush him out to release a new tape to Al Jazerra to better narrow down his whereabouts, for example?
You are right that the chatter does not make sense due to its nature of raising expectations too high.