The sales from Grey Scale will stop very soon I believe. A big chunk of the recent sales could be (hopefully are) from the 1.3B USD Gemini liquidation. That has to be sold so creditors can be paid.
Once that is digested its all upside. We will know when its done, as we will suddenly have a massive inflow / outflow imbalance.
Any other sales, would simply be GBTC holders wanting a lower annual management fee, and so most of that would be money flowing from GBTC back into other ETFs, and GBTC could, if it wanted, simply reduce its fees to retain such funds. (Right now its more worth their while to charge higher fees and hope withdrawals slow, given how much they make in fees).
How close are we to this tipping point? I believe very close. And, that downward move we saw could be just as sharp in the other direction.
Have faith my friends - in time, zoomed out, moves like yesterday a blip in the long term big scheme of things...