However, asked about Thiago in an interview with Welt am Sonntag, Rummenigge replied: "It looks like he will leave us.
"It was important for him that he showed that he can play well in the big games.
"When it comes to that, it's a finish that hurts a bit. I expect an offer for him in the next few days."
He may not be the only Spain international to depart the Allianz Arena ahead of the 2020-21 campaign.
Defender Javi Martinez also appears to have his heart set on pastures new, with Rummenigge confirming Bayern would not prevent him from seeking a move.
"Javi thinks about leaving us. It will be difficult for him now, too," Rummenigge added.
"His contract is still valid for one year and we have given him to understand that we are not going to put any obstacles in his way."