Though I disagree with the route SE has taken in dealing with bots, teleports, hackers, spammers, mules, and gil sellers (letting them run wild while they "collect data"), I understand it is what they've chosen to do...and if I am to continue playing FFXIV I have to deal with it.
However, there is something SE can do right now, today, to stop the RMT from bringing the whole system down around them. Disable all trade.
Turn off the Market Boards, disable direct trade, and disallow sending items via mogmail. Allow players to only buy and sell to NPC merchants until SE can figure out just what in God's name they are going to do about this epidemic.
I know this sounds drastic...but the problem is that bad. Drastic times; drastic measures.
Take away the gil sellers market and the gil sellers will leave, its that simple. Use the time to find their accounts and ban them.