Sancho has come on leaps and bounds since joining the Yellow and Blacks from Manchester City in August 2017 for a fee reported to be around £8m after failing to nail down a first-team place at the Etihad Stadium.
The 19-year-old has lit up the Bundesliga during his time in Germany, scoring 18 goals and providing 29 assists in 64 appearances so far.
Sancho has since become a full-time England international and he scored his first goals for the Three Lions against Kosovo earlier this month in the qualifiers for EURO 2020.
Sancho’s stock has risen so much that he was linked with Manchester United in the summer with Dortmund later confirming that a big offer from a top European club had been rejected.
Zorc has however confessed that given Sancho’s incredible rise, it will be difficult for the club to keep hold of him much longer, despite signing a new four-year contract exactly a year ago.
Asked about Sancho's future, Zorc told German publication Kicker: "No decision has been made. But you don’t have to be a prophet to know he won’t play here for another five years.
"But he knows full well his positive development at Borussia Dortmund and I doubt that would be possible with top English clubs.
"We trust the players very early and are not afraid to let them play.”
Zorc added: "He's an instinctive footballer, a street footballer. He's always a footballer, but he's always setting new limits.
"He does not sit back satisfied. He wants to play football successfully and beautifully. That alone is his motivation.”
Dortmund will travel to Czech Republic, where they will face Slavia Prague in the UEFA Champions League on Tuesday.
