If they do find another compound with the same effects as MDMA it seems clear that it won’t have a structure like MDMA, hundreds of substituted versions of MDMA have been tried and whilst almost all are active, they are not so similar in activity.
Well Nichols tried that with the aminodines and most of them were totally inactive. MDAI was the best of them but not easy to synthesise so was almost never on the market. Others like 2-AI, 5-IAI and several others were fucking garbage. MDAI also needed a stimulant adding for optimum effects.