GMO debate will be settled by development of crops that will be order of magnitude better than existing varieties. It is easy to dismiss the current GMOs that are a bit cheaper, but something like non-toxic cassava, perennial wheat, or twice more productive variety of any staple crop used in poor countries will get widespread use despite all protestations of anti-gmo people because it will save lives in an apparent way. And after some time people in rich countries too would have to accept that gmos are useful.