You're right about Rannocchia, somehow I missed him on the list. But I'm 100% sure he's the first to go, together with Astori. Only 8 defenders will remain (Maggio, Abate, Barzagli, Bonucci, Chiellini, Ogbonna, Criscito, Balzaretti/Bocchetti).
Cassano? Impressed way more since his come back than Aquilani. He contributed in a significant way in the last games of the season, whereas Aquilani was just not his usual self. Out of form and uninspired. Whereas Cassano looked motivated and hungy. His form increased rapidly game after game, he'll peak in the EURO's. That's why he's there.
Balotelli? Maybe not a starter this season, he has harsh competition, but he had a good overall season. He was pretty decisive in Man City's title with his role as super sub. Which Italian striker should've been called up instead? Did Pazzini have a better season? No. Gilardino? No. Amauri? Hell, no. Matri? Good season, but better? Doubtfull. Right choice to call Balotelli IMO.
Most Italian strikers had a bad season, hence a good choice to call up youngsters who have played a good season, they're motivated, eager to impress: Borini and Destro deserve it, although I think one will be scratched from the list (Destro).
6 or 7 midfielders will remain on that list: Pirlo, Marchisio, Nocerino, Montolivo, De Rossi, Motta and maybe Schellotto for width (or else, Cigarini). All deserve it more than Aquilani IMO. Heck, even Rigoni (Novara) or Pinzi would've deserved a call up, they have performed consistantly this season.