Where do you think the money comes from in a fiat backed system? Answer: DEBT! You assume that the central banks intend to sell their holdings at all. With the BoJ making up the majority shareholder of most of the Japanese economy, can they are in a position to DICTATE how their corporations operate. The bigger worry should have always been the rampant debasement of the worlds respective currencies while incurring EXPONENTIAL levels of debt that could never be paid back at the expense of future generations. Japan is leading the charge with regard to the global stimulus experiment. So far, it hasn't worked... but we have witnessed a rise in social unrest, historic wealth inequality, and volatility in currency markets on a global scale.
What do you think happens next???
Watch what the Federal Reserve has done. They wait for maturity of the bonds so they are not sellers. They have also rotated longer duration bonds for shorter duration bonds and then hold those to maturity. The process of selling the longer durations is offest by the shorter duration buying so the disruption of normal markets is not too bad. The European Central Bank is doing the same when bonds mature - they replace them with shorter duration bonds.
Now Japan has done something different in buying the ETFs. They cannot play the duration game. We do not know what they will do because they are just holding. The least disruptive way of selling will be to sell equity ETFs and simultaneously buy Bond ETFs. We will only know when they start doing something.
If your thesis is correct, we should be seeing a wave of social disobedience in Japan. We are not. There is a lot more to Japanese culture that explains why things are different there and why the people put up with such long periods of recession. I woukd love to know what it is as it would make investing easier
BTW I do not appreciate the way you write as if I am an idiot. I understand this stuff a lot better than most. A long career in the industry made me learn