As noted
here by gooselee:
Effective August 15, 2016, we are updating your Cardmember Agreement to state that, for any charges you make in a foreign currency, AE Exposure Management Ltd. ("AEEML") will convert that charge into U.S. dollars.
I likewise wonder if this will result in any changes to the current Amex exchange rate performance? It is certainly possible, given that the new phrasing of exchange rate calculation says "If you make a charge in a foreign currency, AE Exposure Management Ltd. ("AEEML") will convert it into U.S. dollars on the date we or our agents process it" but there is still the phrasing about previous business day(s), etc, so maybe not.