I think also, technically speaking and in terms of efficiency, A320 Neo is playing catch up. It should be more efficient than the current NG, but probably not by a significant amount. As Airbus's days of spamming the market with cheap aircraft are nearly at an end, the differential between Neo and the current NG may not be as great as imagined.
I feel that Boeing have timed their pitstop to perfection, as long as a mechanic doesn't drop a wheel, Boeing will almost certainly be well ahead Airbus.