It would Interfere with other competitions  One of the biggest downsides that this shift of dates would have is the creation of a clash if schedules all around the sports world, fuelling tensions and controversies. No matter in which month the Cup would be played, purposeless conflicts would emerge from this.  Among other potential conflicts if the organizers decide to move it in winter, this being the most endorsed proposal, then there could be a conflict with the Winter Olympics. The International Olympic Committee has warned FIFA against creating a clash with that year's Olympic Winter Games.(1) It would be only in FIFA’s advantage to maintain an open and respectful relation with the IOC. Such a move would create some tensions which could be detrimental for the world of sports.  If, however, the officials decide to move it in anytime during the year, this would create conflicts with the national championships. This could have a tremendous impact upon them, as the World Cup is a long competition. If you add the pre-preparations and the exhaustion that players feel at the end of it, you realize of its impact upon national championships.  This is very important as it will create purposeless conflicts between national federations and FIFA. This will happen due to the lose-lose situation that the federations will be put in. They either end the season abruptly for the world cup, resulting in an extended season (ironically) pushing some games into the summer heat or continue with it as it is. This would be also problematic, as top teams which have players who are also in national teams would be extremely disadvantaged by the sudden loss of their most valuable assets. As a result, conflicts will be created even between football clubs and national teams, as the clubs might refuse to let certain players go to play at the World Cup.  No matter the situation, the shift will bring a lot of disadvantages to FIFA and its partners. The best solution is to leave it in summer where it doesn’t interfere with any other sporting competitions.  (1) “FIFA confirm winter World Cup talks”, ESPN, September 23, 2013