Speaking at the Council on Foreign Relations, BlackRock (BLK) CEO Larry Fink says it's possible cryptocurrencies in general, and Bitcoin (BTC-USD) specifically can "evolve" into a global market asset.While crypto has caught the attention of many and gets plenty of headlines, says Fink, it remains a relatively small asset class. To put numbers on it, Bitcoin has a market cap of $344B versus, for instance, all the gold in the world valued at somewhere around $10T.While it's one thing for Paul Tudor Jones and Stan Druckenmiller - iconoclastic hedge-funders more or less running their own money at this point - to embrace Bitcoin, it's a whole different story for the head of the world's largest asset manager to do so. Fink's "endorsement" comes a few days after Rick Rieder, the CIO of BlackRock's fixed-income business did the same.Bitcoin is flattish today at just a hair over $19K.Previously: Bitcoin survives Thanksgiving