"Runes Reforged", who thought to call it this? It's a slap to the face for the old system. You can say this is masteries reforged, but this new system has no runes involved. None at all. Runes gave flat stat improvement while masteries gave improvement in specific situations or under specific conditions. The new system mimics what masteries were, nothing like runes.
Regardless, they will never revert, I would bet my entire life on them never,"reverting", removing the changes made and going back to the old system. They've sunk too much time and money, time = money as well, into this project for them to just roll it back. Riot is a business and money comes foremost, revering would be like flushing all that money down the drain. They may make a step forward in improvements, but they will never step back.