The German club's relegation from the Bundesliga and Kabak's poor form look set to wreck their chances of making a profit on the 21-year-old.
Schalke allowed him to join Liverpool on loan in January for just £1m - with the hope the Reds would secure his permanent transfer for an extra £17m.
An underwhelming stint at Anfield, consisting of just 13 appearances, meant Jurgen Klopp refused the option to enact his purchase clause.
BILD says a number of clubs are tentatively interested in a deal.
It is speculated that a bid of £13m should be enough to tempt a transfer.
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