Well I'm going to go out on a limb here and suggest Simoncelli, Bautista, or someone like that will replace Hayden next year, in much the same way that Stoner went quickly up the tiddly/2fiddy ranks before the big bikes. I don't reckon they will persist with anymore GP riders, as in my mind it is beginning to show that once they've spent a bit of time on the other bikes, most of the riders have difficulty adapting to the Ducati. I stand to be corrected here, but I think Stoner was an exception to this, and progressed quickly onto the Ducati before getting too used to the other machinery. They would adapt more quickly to the Ducati coming straight up from the smaller ranks. Look how quick Lorenzo is now - albeit he crashed a bit, but he is getting better. Plus they wouldn't have to pay as much, and these young fellas still have pretty big nads as soon as they step up.
Just my 2 cents.