I personally don't think the Amway ruling needs to be reexamined. It needs to be ENFORCED, much like the Omnitrition clarification.
AFAIK, NONE of the major MLM companies actually pay commission on retail. They actually pay on WHOLESALE (ie. purchases by the affiliate), not purchases made by the consumer i.e. retail. As a result, they are indistinguishable from product-based pyramid schemes. And enforcement of Amway Safeguard Rule subset: Ten Retail Customer Rule, as well as periodic audits (also established in Omnitrition case) would have clearly separated the two. But no, DSA and FTC basically pretended that Omnitrition decision never happened.