What is the "lower limit" to negative interest rates in the euro zone?

Many investors wonder how far long-term interest rates can fall in the euro zone, and whether they can become even far more negative than now. There is a "lower limit" to negative long-term interest because: Below a certain level of interest rates, all savings switch to cash; As the household savings rate fall s , the income effect (households saving more to offset the fall in interest rates) disappears below a certain level of interest rates ; It starts becoming worthwhile to take currency risk on the dollar or emerging currencies to obtain higher bond yields in these currencies, leading to massive capital outflows and a depreciation of the euro that drives up interest rates.