Though he doesn't play it often for Arsenal, I'm confident that Nasri could play the deeper CM role. He's put in good performances there for Arsenal and apparently plays there for France sometimes too. It's not just that though, he's a very clever player and is always aware of what is going on around him.
He's no pushover either, and I watched him two seasons ago against Barcelona and thought he looked a man amongst boys, in that Arsenal side. He took that game by the scruff of the neck and worked extremely hard, even when the rest of them looked pyschologically beaten. Personally, I see him as a natural replacement to the current Giggs.