The long run effects could be positive. The shock pushed many firms to adopt new technologies that may be cost effective in the medium run and increase potential output and welfare (less time commuting, more efficient meetings, etc). Such beneficial effects have to be weighted vs the medium run consequences of the scars that will be left by the shock (higher public and private debts, more unemployment). My main point is that there are forces pushing both ways, even though in the long run I do not see why the negative ones should we. It seems feasible to go back to doing whatever was done before the shock. Of course there is a lot of uncertainty on how things will work out as it depends on key policy choices.

I agree with the ECB analysis that the overall volume of trades is too small to matter. The development of derivative markets based on cryptocurrencies might affect the stability of their prices either way (e.g. creating a market to absorb bursts in demand for a fixed supply factor (e.g. bitcoin) might stabilize its price).