I think he's a starting point guard in the league. With the right players around him, his defensive lapses can be mitigated and he provides enough offensive value to overlook his slow feet. Only problem: nobody wants to take on salary right now.
I'm not sure what Colangelo's plan is for the trade deadline but I do hope he has one because the Raptors, unless they defy playoff folklore and explode for 115-120 points/game, are not ready to win a playoff series.
Calderon's departure would have little impact on the court this year. If anything, it frees up Hedo Turkoglu to take a more active role as the primary ball-handler/playmaker (something he has griped about this year) in specific situations, which could actually improve the team, creating more mismatches and slow herky-jerky pick-and-rolls that defenders are not accustomed to seeing.
Off the court: huge. If the team can exchange Calderon for expiring contracts this year (a move I would be fine with), the Raptors increase their cap space to about $15 million this offseason and much more in the following offseason with Reggie Evans and Marcus Banks (finally) expiring.
After (potentially) re-signing Bosh and accounting for the luxury tax threshold going down, it leaves the team a bit of space to tinker with the roster.
Expiring contracts for Calderon is wishful thinking but I think it's fair value when considering the back-up role that Calderon has been relegated to since his return from injury. Expiring contracts are a non-committal return that won't hinder the team's chances at winning a playoff round this year while relieving them of cap duties in the years ahead. It's ideal, which is exactly why it won't happen.
Biggest problem: who really wants Jose Calderon?