"Clearly it's a coordinated, grand investigation. I would expect it's going to continue throughout this year," Gottlieb said. He is representing PlexCorps, which faces SEC fraud charges regarding its initial coin offering.
About 80 firms have received subpoenas so far, according to a source. CoinDesk also reported a similar estimate, citing lawyers.
The SEC did not immediately respond to a CNBC.com request for comment.
Arrington said the regulatory uncertainty and SEC investigations have caused some of the best cryptocurrency projects by U.S. teams to move offshore. "That's a shame," he said. "The U.S. has just frozen itself."
As an investor, Arrington said he is also more interested in cryptocurrency projects coming out of China and nearby countries. "The stuff coming out of Asia is uniformly high quality," he said.
Regulators around the world have approached cryptocurrencies in different ways. China officially banned initial coin offerings in September. Japan implemented licenses for cryptocurrency exchanges in April. South Korea confused investors with its back-and-forth on regulation and as of late January has implemented a ban on anonymous trading accounts.
In the U.S., the SEC faces the same challenging task of determining regulation for a new, digital product that is evolving quickly itself.
"I hope they don't go [down] the slippery slope of trying to classify tokens because it's a grey zone throughout," said William Mougayar, blockchain investor and author of "The Business Blockchain." "Rather, focus on requiring disclosures that are well-defined, while not being too restrictive yet."
Bitcoin was around for about eight years until sales of new digital coins, or initial coin offerings, began to take off. They raised more than $5 billion last year alone, according to financial research firm Autonomous Next. However, the projects for the so-called initial coin offerings often barely exist beyond an online whitepaper.
Earlier this year, SEC Chairman Jay Clayton wrote in a joint op-ed with the chairman of the Commodity Futures Trading Commission that the SEC is devoting "significant" resources to the ICO market. Last summer, the SEC issued an investor bulletin warning about the dangers of initial coin offerings.
Gottlieb said the most likely result of the SEC investigations is a "hodgepodge of court decisions" rather than regulations or laws, which could both take longer to develop. "Ultimately you may have to resolve some things in the Supreme Court," he said.
The "Howey Test," which tends to guide current views on whether an asset is a security, comes from a 1946 U.S. Supreme Court case.
"It seems highly likely that these subpoenas will result in some tokens being found by the SEC to be unregistered securities," said Ryan Schoen, senior financial services policy analyst at Washington Analysis.
Schoen said he expects the exchanges involved with trading the unregistered securities will come under SEC scrutiny next.