Assuming you're being serious, while I'm sure it would be a big blow, and Berra is a decent CB, he's some way from the best in the league. As an individual, I wouldn't put him in the top five, possibly even ten, CBs in the league. To state the obvious, he's behind Grant Hanley for one.
However, it's obvious that he is perfect for your system and McCarthy gets the best out of him as shown with Wolves. He is also very dangerous from set pieces. And reliable. He's basically the perfect McCarthy player. So while I don't think he's necessarily the best CB in the league, I doubt there are many CBs in the league who would perform as well as he does in that system. In other words, I get what you're saying...
I don't think you need to worry about an injury to him though, I can't remember him ever getting seriously injured? Unless they're prone, CBs are least at risk.