His father also said he wants to stay for now and sign a new contract IIRC. Dortmund certainly won't sell. They lost gotze and won't stand to lose another key player hence the standoff with lewa
That's a possibility indeed, but the Lewa case is unusual. I mean Dortmund usually always sell for a price. But Herrera would be a good signing, anyone to slightly improve midfield would be a bonus.