The experienced midfielder remains a key player for club and country, but the 46-year-old believes he is on the decline and could lose his Germany spot shortlyBayern Munich midfielder Bastian Schweinsteiger already has his best days behind him.
The influential midfielder has been a key figure for both club and country in recent years, but Thon feels that the 28-year-old is past his best.
"Schweinsteiger is a player who will only further decline simply because he no longer has the speed from before," Thon said to Sky 90.
"You need speed and aggressivity in his position, although I have to admit that Schweini is doing a good job. He is showing other qualities and could perhaps stay at this level until the 2014 World Cup.
"After that, he will probably follow the same path as Michael Ballack with the national team. It could even [be] sooner. Schweini's mainly playing simple vertical passes and cannot beat his man anymore. Borussia Dortmund's [Ilkay] Gundogan brings more to the table at the moment."
Gundogan impressed when he took Schweinsteiger's place in Germany's 2-1 friendly win over France last week.