Well if the GK economy is a joke to you, then fine it's a joke to me as well. Lets pretend everything's fine, like people have for the past 2+ years. As for USDing, you don't see or hear of it much cause yeah YOU GET BANNED. So it might seem rare to you, but only god knows what's going on. I also agree with you Sean, rares are a HUGE part of the economy at this present time. Most of witch lie in the hands of already very wealthy people.
As far as ideas, a few could be as a stated above in my other post having the diamond NPC value 500 plat. New content such as new dungeons that people can go to and farm like HHW/HHE is. And actually implement some useful items that drop there. Of course we don't want them to be very common, but some newer items that can be obtained by people that don't have these "rares" you speak of. Then maybe even middle class / lower end of the totem pole people can get their hands in the cookie jar to get other useful items they may need. Even in the present dungeons, the value on drops could be increased making farming more worth while instead of just using alchemy on all the drops.
No matter what you do, unless you permanently remove diamonds from the server they are always going to be a form of currency. So if you don't want them to be the main currency, just have them being able to be sold to the vendor as another type of DoPV. All lowering the value of diamonds is going to do for the economy, is make it twice as hard to obtain items you need (WITH PLAT)
For example, 1 RoW to the best of my knowledge was around 4k Diamonds when they were the main currency. Which is 2 million plat. Leon had mentioned he'd sell a RoW for about 1.5-2m plat. Now if the diamonds value stay at 250 plat each, you're going to have to work twice as hard to obtain that RoW. Not saying all your plat is going to come from diamonds, but this is just a rough estimate of how things would work.
