I've already seen people trying to buy up diamonds in bulk and what not, what good does it do to have a bunch of ppl bringing over loads of diamonds? How many people (with wealth) are going to bring over wood planks/cobble/wool/etc? It either has to be all or nothing, any combination of the minas/items options would have negative ramifications for the economy, unless a new alternative is found, and Zombez has a solid idea.
What are people afraid of? You're here to develop and play your character. If you're a mega wealthy merchant, what is to stop you from doing it again? It is your characters profession, and should be viewed as an interesting challenge with many new rp opportunities, not as: "wow this is unfair that I can't sit back on my wealth anymore."
A semi-unrelated point, and this is all strictly my opinion, but I view people in this boat as a max lvl character in an MMO that has alot of money and everything they need, but fail to 'play' as much as they once did, instead just sitting back and using the game as a social tool, and raid every once in a while.
Furthermore, I believe the ideas listed in the link provided also need to be looked at: here