The only way RMT will ever go away is

1. Remove the Market completely
2. Remove player trading
3. Make Gil Unique and Untradeable and only obtainable from npc'ing items, quests, leves, fates, dungeons, etc

Completely 100% remove any method for RMT to give you gil, that's the only way RMT will ever be 100% gone. But then they'll just level to 50 and sell titan runs for Real Money. E.g. you go on their site, pay them $10, and they log on your server with relic +1's and run you through Titan HM.

Where there is a demand, their is a supply.

As long as people, even 1% of the player base want RMT based services, they will not go away.