As most of you are saying, Xavi is irreplaceable. But there are players who have a similar skillset and given time to adjust to the Barcelona way could become masters of the midfield... ATM Gundogan would be the best fit because of his vision, passing range, tenacity, ability to dribble out of tight situations and overall ability to control a match. Samper & Torres have the potential but are behind Gundogan for the time being.