To get past Sobers, one would have to average at least 60+ in nowadays. He had led the batting charts for years.
No, Shakib cannot replace Sobers unless he averages 60 and continue taking wickets like right now. That means scoring centuries in test right and left. That is too much to ask with the support or the top order platform he needs. 26 test and 2 centuries wouldn't take him to the top five discussion. Plus he is not averaging in the 20s with the ball either.
Jack Kallis has a bigger argument but nah. Sobers was a tremendous fielder as well. Unless Kallis gets 6 more centuries before he retires meaning equaling Tendu he will not cross Sobers. Sobers was undisputed #1 batsman of the World for a long time. Kallis has competition in his team Amla let alone the World.
The Weak can never forgive. Forgiveness is an attribute of the Strong." - Ghandi.