When the Chicago Fire host New York City FC in the MLS season opener Saturday night at Soldier Field, home field advantage will begin to take on new meaning. The 25-year-old, oft-overlooked soccer team may soon be the only game in town, at least at the iconic lakefront stadium, as the Chicago Bears prepare to build a new venue in Arlington Heights. With the MLS gaining significant momentum in markets across the U.S., the Fire, one of the league’s worst performing teams for much of the past decade, have a chance to grow their fan base and perhaps finally matter in Chicago. “This is a once-in-a-generation opportunity for the Fire to become far more relevant and to have far greater attendance at their games,” said Marc Ganis, a Chicago-based sports marketing consultant.