Watzke said bvb expect a decision this month. Means if gündogan doesn't make up his mind, bvb will.
Bvb are in a good position to negotiate right now thanks to Jojic stepping up. Gündogan is highly unlikely to just walk back into the team now. So he'll have the choice - he can renew, not renew and leave this smmer, or not renew and stay for one year with the huge risk that he'll spend a majority of the season in the stands, which will further divert interest.
It would honestly be best for him to renew and stay at Dortmund. Although I wouldn't object if he becomes a Barça player...