I have been a member of Airmiles from the start over 20 years ago and have seen a few changes but suspect there will be some smoke and mirrors used to hide some sort of devaluation and overall Iberiaisation.
In the beginning flights were paid for using miles with genuine government taxes paid in cash. Howeve a big advantage was that a flight paid for in miles did not require a Saturday night stay as all cheap tickets did in the days before LCCs. I even managed to fly on the Deuche BA SAAB 2000 from Gatwick to Bremen which was supposed to be all business class for the standard economy miles, although the check in agent did write "no lounge access" on my boarding card. They also had out of season promotions on long haul routes.
The current system is good if you can find a destination you want to fly to with BA and only want a straight return ticket.
The proposed replacement will be like most FF schemes with mileage points valued like Zimbabwe Dollars with taxes, fees and charges based on the what we can get away with charging principle.
The big test for the future of the scheme will come when the retail and credit card partners contracts come up for renewal. The partner credit card will then probably be one issued by that bank known for fraudulent transactions that shares a name with a ferry port in northern Spain.