According to MISH trend analysis negative interest is coming. At least I know I am not alone in this expectation.
From article: "Denmark's certificate of deposit rate was chopped by a quarter point to where CDs now yield minus 0.2%. Which is to say holders of these certificates willingly pay the Danish government a fifth of a percentage point for Denmark to hold their money.
What would be implication on mortgages and economy need to be investigated, but I will not try to lock my mortgage just because rates are low. It is a government who need houses where people live so vassals pay will continue going to them.