Visa is feeling the heat from payments startups, digital wallets, and crypto—and Wall Street is starting to worry.

Mizuho analyst Dan Dolev downgraded shares of Visa (ticker: V) from a Buy to a Neutral rating on Friday and cut his price target from $255 to $220, citing threats to the company's growth.

"We are concerned that secular challenges from new competitors willincreasingly nibble at Visa's volumes," Dolev wrote in a note published Friday.

Visa is a top Barron's stock pick for 2022, trading at 30 times projected earnings of about $7 a share in its current fiscal year. The company is a "juggernaut of the payments business," Andrew Bary wrote, processing more than $12.5 trillion in transactions a year. Much of Wall Street rates the stock a Buy with a median price target of $271. Shares traded around $217 on Friday, down 1.3%.

Still, threats to Visa and its chief rival Mastercard (MA) are mounting as consumers switch to new payment platforms and digital wallets that could bypass the card networks or slow their revenue growth.

Among Dolev's concerns: Growth drivers from people abandoning cash for cards and online payments may wind down by the end of this decade. That shift from cash accelerated during the pandemic as online shopping, debit, and other forms of card payments picked up. But the trend has now picked up so much that it won't help Visa much beyond 2030, potentially affecting 45% of Visa's historical revenue growth, Dolev estimated.

Visa also faces more competition for card transaction volume as rival payment platforms gain traction. One threat is Plaid, a start-up that is building a payments bridge between banks, consumers, and merchants, potentially cutting out Visa as a middleman.

"Plaid …is a meaningful medium-term threat to Visa's debit business," wrote Dolev. "The worry is that over time, Plaid could offer an alternative to Visa's debit rails."

Visa tried to buy Plaid for $5.3 billion in early 2020 but backed off after the Justice Department sued to block the transaction on antitrust grounds.

Other threats to Visa's business include peer-to-peer payments through digital wallets, including stablecoins and cryptocurrencies; a new real-time payments system called FedNow, and payment services like "buy not pay later," or BNPL, that could bypass the card networks.

The confluence of threats could trim Visa's revenue growth by 1 to 2 percentage points annually through 2024, Dolev estimated, pushing growth closer to 13% than the 15% now embedded in consensus forecasts. He trimmed his revenue forecast for Visa's 2023 fiscal year to $32.1 billion from $32.5 billion.

Visa, of course, isn't standing still under these pressures. BNPL transactions may still run on its card systems. It also is working its way into digital wallets and developing new revenue streams with its "Visa Direct" system for real-time payments.

The company also sees revenue opportunities in cryptos and stablecoins—tokens designed to maintain a fixed value of $1.

"What we can do is be the bridge between the crypto economy and the fiat economy," Vasant Prabhu, Visa's vice chairman and chief financial officer, told Barron's this week.

The company is working with crypto exchanges like Coinbase Global (COIN) to facilitate transactions; account owners can use crypto as funding for a card payment after the crypto has been sold and converted to cash automatically, for instance. Visa is partnering with more than 50 crypto wallet providers and is developing a "native digital currency" settlement on its card networks.

Prabhu said Visa is also working with banks to develop crypto deposit accounts. "A lot of banks understand that their customers would like this, and they realize they may be losing deposits because money is moving out of bank accounts to crypto platforms," he said. "There's a lot of interest in figuring out how to do this."

That won't happen overnight, though, since banking regulations on crypto aren't keeping up with customer demand. Investors, for now, may need more convincing that Visa's new revenue streams will offset potentially slower growth in its core business. Visa stock is up just 2.6% over the last year against a 23.5% gain for the S&P 500.