Personally I doubt that this will become an issue.
Easy goldsinks can come from repair costs, convenience items, flavor items, etc. Anyone who played vanilla wow and raided can understand this concept easily.
When we're dealing with the item side of the economy, many top tier items will be salvaged just so that players can have a crack at making that godly once in a lifetime crafted item.
Another easy way to grind top tier items out of existence is a very simple one, make the majority of rare legendary items ethereal, this will provide a player an incentive to use the item temporarily, then salvage it before it breaks into worthless mush.
The loot table for Diablo 3 will by all assumptions be astronomical, item saturation won't be anywhere near as much of an issue so long as blizzard can keep D3 dupe/bot free. I think most of the concerned players are expecting D3's economy to be similarly broken to Diablo 2's (rampant botting, duping, maphacking)
Even if players DO start to saturate the economy, blizzard can simply lower drop rates on top tier items.
If all else fails, there's nothing stopping blizzard from implementing a ladder system for Diablo 3. Don't sweat it until it actually becomes an issue guys.