I don’t think this is going to happen, but it wouldn’t surprise me one bit if it did. I give it a 10% chance at most. I’m sure there are many in the Obama camp who wish he/they hadn’t picked Biden who is the very antithesis of change, when change is your central theme, especially a guy who hoped to finish FOURTH in Iowa. The pick looks exceptionally bad with McCain’s pick of the electrifying Sarah Palin.
Several things would have to happen for this succeed-here are just some of them 1) Biden would have to agree to it, unlikely since he reportedly campaigned so hard to the VP pick. 2) They would have to keep it ultra-secret, even one Biden guy spilling the beans would be disastrous 3) They would have to come up with something that passes the smell test whenever one will be very suspicious of this happening. 4) It would have to be something that is new, lack of proper vetting charges would quickly prop up if it was something old or easily detectable. 5) Hillary would have to pre-agree to the whole thing, doesn’t do them a damn bit of good to dump Biden for Hillary when she doesn’t want it. 6) They would have to keep Bill Clinton’s mouth shut about it. 7) They would have to find at least a couple of doctors willing to collude on this and it will look very suspicious if it is not Biden’s regular doctor(s) or the doctors at Bethesda.
I’m not even remotely wishing ill health on Joe Biden. I’m just pointing out this is not outside the realm of possibility.