The Bayern forward told the Daily Star: "I don't know if Arsenal can keep him if they are not winning things. It's always difficult to judge that about another player.
"But you can see that Wilshere is a very big talent and he is only young still. He's just 21 years old. He will definitely be a big player."
Manager Arsene Wenger has previously suggested that Wilshere could be a future club captain.