If Xabi can win either Bundesliga or Europa League, it's better for Manchester United to hire him and kick the bald guy. Manchester United already lose their legacy as one of toughest team in Premier League. They need to find a good coach who can able to develop the whole team, just like Xabi who wasn't sign many players, but he develop the existing players with a new strategy.
What makes you Think Xavi is going to leave Barcelona and come to Manchester United? There is every tendency that he is well paid in the Spain than they would do in Manchester United and even if they offer to pay him more than in Old Trafford, what if the conditions are too much to bear? What if they gave him a contract to make sure he lead the team to the top of the table before the end of the season and must win the Champions league or Premier League next season, if this condition cannot be delivered, I don't think he is going to come to their rescue.
Barcelona is only slightly different from Manchester United, they aren't too good the half of the season they have demonstrate so far, look at where they are sitting now and look where they were sitting last season, nothing less between first and second, they top the league throughout last season but the way they are going now. They are wearing out and I fear how they are going to cope when the Champions League resume by February.