More ways to make gil in the game = greater inflation
Quite honestly, I don't think there is any problem with the gil influx in the game.
New characters make tons of gil through quests, which in turn they use to buy stuff in the AH. That money (even though it is cut a little), then goes into the hands of the senior characters to be used again.
Considering that we can expect new characters to be created frequently, we can also expect a steady influx of gil through quests.
Heck, you can even create a new character yourself to stimulate your server!
Furthermore, plenty of items can be turned to NPCs for gil. With the big player base on any server, this is a non-negligible influx of gil.
Just selling to NPCs the lesser crappy items you get and other lesser crappy items from gathering can help any character sustain itself.
Honestly, this is a non-issue. There might be some tweaking to do to increase/decrease the influx of gil, but it is not to the point where the whole economy will crash.