I personally think we should assess his form at the end of the season and not succumb to snap judgements. If he's still making blunders by the end, then I think we should look at our options (Alex, for example) and have Bonucci as a bench option for the 12-13 campaign. He'd be a very good bench option, in fact.
I'd like for us to move for Alex, but I'm also a fan of not abandoning players too quickly. Bonucci had a very assured performance v Udinese. It might be a sign of things to come...