Liuzzi has a contract for 2011, however as we know these things are always negotiable. I think Force India would be daft not to go for Hulkenberg, though money (as ever) may play a role. If they’re happy with becoming a Mercedes training ground we could plausibly see both Hulkenberg and di Resta at Force India in 2011.
You haven’t mentioned the Sutil factor of course. He might retain his drive or he might be dropped. Personally I’d go for the latter, but again, money talks.