In an interview to appear in Wednesday's Stuttgarter Nachrichten newspaper, Weber also ruled out Schumacher moving from Ferrari to McLaren, powered by Mercedes engines.
"I can't say now that it is with any certainty but I think that the end of 2008 is probably the end for him (Schumacher)," the paper quotes Weber as saying. "But I could be wrong."
He added that Schumacher, whose Ferrari contract runs through 2006, would not decide his future plans until next year. Weber also said the German driver was not going to McLaren.
"Just stop it now," Weber said. "Right now I can rule out this link. It doesn't make any sense... First of all, Michael feels totally comfortable at Ferrari. And secondly, Schumacher wouldn't be better to market at Mercedes than Ferrari.
"Mercedes symbolises luxury cars and Ferrari sports cars -- and that image extends to every corner of Brazil. At Ferrari, everyone thinks about races, motor sport, Formula One. For a driver's image that's much better."
Schumacher's five-year reign as world champion was ended by Spaniard Fernando Alonso, who became the youngest champion in the sport's history in Brazil last month. The German is third in the standings behind Alonso and Finn Kimi Raikonnen.
