This still would drive up the value of USD, it just allows for the depreciation associated with the sale currency to be spread out to a degree. But the issue w

This still would drive up the value of USD, it just allows for the depreciation associated with the sale currency to be spread out to a degree. But the issue with this is that there are only a few currencies backed by economies large enough, relative to the US economy, to be able to trade for sufficient quantities of USD without really impacting the exchange rate. If the impact is large enough, the only good solution is for the fed to agree to a currency swap.