I'm quite sure that this will never happen for reasons as to it make people do a lot of work to buy the time with gil than actually play the game.

So no this will never happen it would cause a big imbalance in game and would take fun out of it because people will be farming stuff all day every day to make the gil they need to buy time from some one.

Its not needed so stop arguing about it and if you really need something like this because you can't afford the sub...then get a friking job real life job sell some of your things for go food for a day because if your already a active player you can afford the sub so just play the game.