The Patriots could replace Tom Brady with Colin Kaepernick ... so says NFL legend Cris Carter, who says he KNOWS Robert Kraft's team is "very, very fond" of the QB.
Tom's fresh off his sixth Super Bowl ring ... but he's 41 years old -- and there's no clear successor to him on the roster if Father Time somehow abruptly wins their yearly battle.
Enter Carter ... an NFL Hall of Famer and overall plugged in guy who says TB12's eventual replacement ain't in this year's draft -- it might be in free agency .