Except the 250th celebrations will be nationwide and there will certainly be celebrations in every American city. The Bastille Day celebrations happen every year. It was not a particularly significant celebration with it being the 211th anniversary in 1998. And the FIFA World Cup finished on the 12th July, two days before Bastille Day, not in the middle of it.
Football is the national sport in France, in the USA it is a minor sport. Will the US be prepared to interrupt such a major cultural event for a soccer tournament?
There was close to a couple of months between the Diamond Jubilee and the Olympics in London - we are talking a day between the 4th July and a likely date for the World Cup quarter-finals. FIFA cannot bring the tournament forward as it will clash with all the European Leagues and no European country, the most powerful bloc, will not vote for the USA if that is what they proposed