Sancho, 26, is out of contract at Manchester United this summer and is currently on loan at Aston Villa, where he has scored once and provided three assists across 34 appearances in all competitions.
United signed him from Dortmund for £73 million in 2021 and are not expected to offer a new deal, though they retain a clause to extend his contract by one year — a complication that could delay any free transfer move.
Speaking on the 19:09 Talk show organised by Ruhr Nachrichten, Kobel was straightforward in his support.
"When he came back to us, his presence did us a world of good, even if the statistics perhaps weren't as good as in his first spell. I'd be glad if he came back to us with that same attitude."
Borussia Dortmund sporting director Ole Book told Sky the winger left a lasting impression at the club through his technical ability and creativity.
Head coach Niko Kovac has held direct talks with Sancho about how he would fit into his system, with those conversations described as positive.
The financial element remains the main obstacle. Sancho currently earns around £250,000 per week at United — well above Dortmund's wage structure. Reports indicate he is prepared to accept a significant salary reduction to make the move work, but the gap is still considerable.
Aston Villa are also considering a permanent deal, keeping their options open as Sancho weighs a future that now hinges largely on whether United choose to activate their extension clause before the window opens.