I tend to disagree. In a bear market, assets are sold and converted into fiat. Investors would dump stocks, dump bonds because default rates would start to increase.
traditional safe havens are Gold, JPY & CHF, Treasury Bonds.
Nowadays many central banks have already set negative interest rates. Cash is charged by banks directly on current accounts. To avoid suffering from these dynamics, cash has to be put to work, or parked.
Crypto did not exist back in 2008 during the last crisis, and asset managers will be happy to experiment it during the next one, because, hell, they are paid to do something with the cash.
The next economic turnaround will see unconventional policies implemented by central banks because all the traditional tools will be useless (rates are already too low). Helicopter money, stock outright buys within a new QE program, whatever can be imagined. So yeah, cryptos might increase in value when wall street turn to the ultimate safe haven. That's if the crisis is contained, and fiat don't just turn obsolete in the end.