The Italy coach has stressed that his focus is on developing the side around the young Azzurri talent, but maintains the experienced forward could still have a part to play.
The Inter attacker has been criticized by the likes of Fabio Capello in recent weeks after he was involved in a row with club coach Andrea Stramaccioni. The 30-year-old was also left out of his national side's last outing, when it drew 1-1 with Netherlands in Amsterdam, but Prandelli has made it clear that the former AC Milan man could still have a part to play in the side.
"The Azzurri story is not absolutely over for him," Prandelli told Guerin Sportivo. "But at the moment, I have to develop the team. If Cassano were there, I would never have discovered Stephan El Shaarawy.
"Antonio is doing well at Inter and for him, just as for others, the door will always be open."
Cassano was recently frozen out of the Inter side following the training ground bust-up with Stramaccioni, although he did feature as a substitute in the weekend defeat by Bologna.
While the Nerazzurri have endured a torrid run of form of late, Prandelli feels Cassano and his teammates still have a strong chance of reaching the Champions League places come the end of the season, and has backed the under-fire Stramaccioni.
"Inter had begun the season with the aim of the Champions League places, and I think that goal is still in full swing," Prandelli said. "[Stramaccioni] is very young, he has to find solutions to every game."