I always hoped until the last second that he would become coach of Argentina....the chances for Messi to win the WC would be 100x higher.
With him as coach I would consider Argentina top 3 to be WC winner.
Coach of Barca ? Apart from the fact of his defensive game, I don't see him having in team players (with exeption of goat Messi) who do not run,
do not bleed, do not spit the soul on the pich, do not fight like warriors. His teams are always made up of 11 warriors, based more on physical, mental strength and discipline than on technique. If he becomes our coach, half of the team goes home (no matter how much the players have been paid).
I'm not sure how much he would do well with a big team, where there are important names and other balances in the dressing room.