Let's get it straight though, Rio will be on the books next season. That gives us 5 quality CB's in our ranks(Vidic, Evans, Rio, Brown, and Smalling), that is more than enough cover except in extreme circumstances. You can't go and chuck £10m or more on a player on the grounds that we might need him if ALL our CB's are unavailable, it's just not something you can legislate for. The cheap, over the hill signing is just pointless aswell.
On Evans, adversity is something most young player's go through, but the talented and mentally strong ones come through and end up better player's. I've no doubt that Jonny will do the same, that's why I see signing someone else as futile. He was class in 08/09 and most people forget, was Vidic's principal partner in our 14 straight clean sheets. He covered Ferdinand extremely well for most of last season, hence our impressive defensive stats in 2009/10. This is his first blip in form, but he'll come good again and become one of the pillars upon which Fergie's next team is built on and the world-class defender we know/he's shown he can be. Bringing someone in would just slow that process considerably aswell as impact on Smalling's impressive development since being given his opportunity, an opportunity he'd have not been given had we had a Shawcross/Cahill/has-been in the squad.
calm down dear.