If I could choose two players to make substantial improvement, it would be Swift and Masten. I don't think it's an unreasonable hope either, given both have shown patches of very good footy.
I expect NN to continue his very good work in the ruck and to become more dominant in the forwardline. I can see him consistently sitting on opponents' heads in the goalsquare.
I'm not too concerned about Weedon's development considering we now have Strijk, Hams (when elevated) and LeCras as forwards offering midfield rotation.
I'd like to see Sheppard follow his current trajectory of improvement.
In terms of surprise packets, Neates is probably as good a pick as any, I reckon. He has a bit of dash and uses the ball tidily. From the little I've seen of him at Claremont, he looks nice and composed too, which should help him make the jump to AFL.