Persistently negative long-term real interest rates: Who is going to hold all the bonds?

We can expect real long-term interest rates to remain negative for a long time in the United States and the euro zone, given the continued very expansionary monetary policy and the normalisation of inflation. Will there be volunteers (households and institutional investors, non-residents, banks) that are willing to hold bonds, or will the negative real long-term interest rates drive private investors/savers to sell bonds to buy other asset classes and then force central banks to maintain large quantitative easing programmes? Recent developments seem to show that since real long-term interest rates have been negative: In the United States, households and institutional investors have continued to buy bonds; In the euro zone, only the ECB has been buying bonds, which tends to confirm our concern that only central banks will be able to buy them.