QE is an anti-deflation programme. Governments are very keen to avoid real deflation because it kills investment stone dead, leading to loss of jobs and a real recession.
The reason why I think a panic is unlikely is that the current bubble is a "search for safety" rather than a "search for return". That's why the Swiss central bank can get away with negative rates - they are charging a premium for asset safety of the CHF. It also compensates Switzerland from the negative effects of its currency appreciating.
Previous asset bubbles burst when the second derivative goes down: when the returns go down, the rush to buy the asset stops and the price collapses.
The rush for safety is different. There's nowhere else to go but other, riskier asset classes. Even trying to hold it as cash has problems when done on that scale.
Negative rates are also I think your leading indicator for the net asset loss that's going to come from global warming. Not just "unburnable" fuel and lost investment in industries that must be transitioned away from, not just the sunken beachfront property, but the requirement to build new renewable infrastructure just to maintain our current standards.
There's a huge investment needed, but since the return it offers is collective and can't easily be captured by the investor it's not going to come from the private sector. Wealth can only be preserved in the context of preserving society, so the wealthy are going to have to take a small haircut in order to preserve the whole.