I hate to see Caldara go but I think people are overreacting. I would be willing to bet that in 3 years our defence is still way better than theirs. As soon as one of our defenders has a bad year he will be replaced the following summer with an out of contract 31 year old who is still great. Thuram, Benatia and Barzagli joined at 29, Cannavaro at 31.
I don't think Chiellini would have been given the chance to develop here if it wasn't for Calciopoli. Bonucci joined in 2010 when established players wouldn't touch us with a 10 foot stick. We rarely give players time to develop anymore. It kind of sucks because prospects are exciting and it's fun to see them develop over time. We want immediate success, and with defence it seems, we tend to play it safe.