Whether or not Michael Schumacher stays at Mercedes beyond 2012 should be decided within the next six weeks, team boss Ross Brawn has revealed.The 43-year-old's contract runs out this year, one in which he has so far performed more strongly than in 2010 and 2011 but had technical failures and incidents.'WE KNOW IT'S COMING...'It has been suggested that Mercedes' protege Paul di Resta, currently at Mercedes-powered Force India, is the most likely candidate to replace the seven-times World champion."We will make a decision this (northern) summer," team boss Brawn said at a Formula 1 Teams' Association forum at Williams' UK team HQ on Tuesday. "We know it is coming and we have to make a decision soon. I think in the next six weeks or so we will have to think about what we want to do next year."With Schumacher's contract running out, the major complication for Mercedes is that its apparent top pick as replacement, Briton Di Resta, already has an agreement in place for 2013 but Force India deputy principal Bob Fernley said the Silverstone-based team would not stand in his way.He said on Tuesday: "We would not get in the way of the career of a driver but there would have to be a commercial agreement in place."