The Islanders were originally scheduled to play an exhibition game at the Barclays Center in Brooklyn on October 2, 2012. That game was cancelled due to the lockout.
The Islanders lease with Nassau County does not allow them to play regular season games outside of the Nassau Coliseum, however that's something that could certainly be negotiated with the County. While the Islanders and the County appear to be on bad terms, having recently publicly aired dirty laundry about unpaid debts, County Executive Ed Mangano has brought in Barclays Center developer Bruce Ratner to oversee the Coliseum redevelopment. Chances are, something could easily get done in relation to a few regular season games. Could the Islanders move permanently earlier than 2015? Certainly possible, but hard to tell at this juncture.