Sancho has only started one Bundesliga game for Dortmund so far this season, but his form during his appearances off the bench have earned him a maiden call-up to Gareth Southgate's England squad for the double header against Croatia and Spain.
The former Manchester City youngster has already registered six assists this season and is understood to be attracting interest from top Premier League clubs.
The likes of Liverpool, Manchester United, Chelsea, Arsenal and Tottenham Hotspur have all been linked with a move for Sancho, and The Mirror reports that Dortmund are aware of the interest and already bracing themselves for offers next summer.
However, the report also claims that Dortmund believe Sancho could be a £100m player in the future, following in the footsteps of Ousmane Dembele.
Dembele left Dortmund after just one season to join Barcelona for £120m in 2017, and the German outfit are hopeful that Sancho could also fetch a nine-figure sum.