Funny, but I have thought for years that arrivals-lounge duty free might be a better option in some ways. Good to see some at last.
1. - airlines get the first shot at selling duty-free goods, as the pax won't have already stocked up before boarding (perhaps the airports won't like that!)
2 - airliners would save the weight of all those duty-free bottles that pax bring on board, which is in addition to checked baggage and hand luggage, but then the airline may have to carry more bottles to sell because of point 1 above some perhaps some of the weight reduction (and fuel saving) will be lost here
3 - definately would reduce the risk of delays due to missing pax. Returning from ATL to MAN in May, there was a queue of about 20 people waiting to be served by just ONE person working in the duty-free shop. Despite joining the queue 30 minutes before departure, we then had to RUN to the gate in order to ensure we didn't miss the flight. And there were people behind us in the queue for on the same flight. Only when we had paid for the duty free did we learn that you cannot carry it to the 'plane at Atlanta - they have to take it to the gate for you. There were around 30 people waiting inside the 'plane for the trolley to come along with their purchases, and it arrived about 30 secs. before the door was closed. Apparently it's quite common for pax. not to get their purchases in time, even though they've been seating and waiting on the a/c for some time, and they then have to obtain a refund (ok assuming you've paid by c/card, but what about if you paid cash?). Ludicrous situation.
The only thing against arrivals duty-free is that pax just want to get bags and go, especially on return flights, and so revenues may drop. Plus, looking around the duty-free shop in departures for the umpteenth time at least whiles away some of the time during delays....