In my opinion it would be a shame for Iannone to be relegated to WSBK. He's way too fast to be let go to another championship. I think Suzuki would do themselves a great service and sign him ASAP.
This is pure speculation. But since it hasn't been 100% confirmed that Vinales is going to Yamaha. It wouldn't surprise me if Yamaha may have been stalling out just to see how Ducati would play their hand. Iannone is way faster than Vinales and is also a proven podium contender. He just crashes a lot and that's Iannone's downfall. But I could see Yamaha picking up Iannone for the second seat.
Now if you ask me who I see developing into a faster and more consistent rider with a possible championship aspiration. I'd pick Vinales over Iannone. I think Vinales will develop into a very fast rider and is already what I would call a "minor alien". He's in the same class as Iannone and Dovi at the moment. The three guys that are right there on the cusp of being in the "alien" category full time.
I think Suzuki should dump A. Espargaro and pick up Rins for the second seat. The only thing I have against Rins at this moment, is he is demanding to talk only to Factory teams. He's not even interested in a satellite team. Which I think is rather bold and someone narcissistic. Yeah he may be leading in Moto2, but you ain't sh*t until you hit the premier class, and he's not there yet. Look at Tito Rabat, I would have thought he'd have more speed than he does here in MotoGP(especially since he did so well in Moto2) but he's struggling big time in the top class. A lot of people think Sam Lowes will do well in MotoGP but if he's anything like his brother on big bikes, he's going to suck.