IMO, Krasic could never be a new Diego - unlike Krasic, Diego actually has a real talent, which was unfortunately grossly mishandled by Juve. Diego had the misfortune to come to Juve during a tough period for the club, and Diego like many artistic Brazilian players are pretty moody and their performance heavily depends on the environment in which they are in - they need to feel the love of the fans and those around them to perform at their best, very much like Robinho and his mishaps at Real and Man City. This is an Achilis heel for Brazilian playmakers but if you wanna get the best out of their talent, you have to find a way to deal with it.
Krasic on the other hand has a talent for one thing in particular and that is to run into the empty space in front of him, if there is any, and then cross or lose the ball or fall for a foul, preferably in the PA. If there is no room in front of him, Krasic looks at loss what to do with the ball and usually either loses it or gives a safe pass backwards.
He would have been well suited for the Premier League 10-15 years ago ... I am not sure he would fare well there now given how even they have evolved their game with all those foreign players and coaches.
The way I see it, Juve cannot lose should they sell Krasic, if there was a mistake they made, it was when they got rid of Diego so quickly.