Privately held Chick-fil-A is not just growing fast, it’s becoming a growing threat to a number of large publicly held chains, including the biggest of them all, McDonald’s Corp.

According to Kalinowski Equity Research, Chick-fil-A could move into the number three spot on the list of largest U.S. restaurant concepts in 2018, which was held by Subway, the privately held sandwich chain, in 2017. That would be ahead of the 2020 projection made by others.

Kalinowski cites Restaurant Business data that shows Chick-fil-A sales up 15.5% this year. Traffic is up 10%.

In 2017, Chick-fil-A’s U.S. systemwide sales were $9.021 billion, up 14.2%. In 2018, that sales total could near $10.4 billion.

“We have long pointed out that Chick-fil-A is the restaurant competition with which McDonald’s U.S. should most concern itself – and by extension, investors should too,” the note said. “But this goes beyond McDonald’s.”

McDonald’s MCD, +0.53% was the top concept in 2017 with U.S. systemwide sales of $37.6 billion. Starbucks Corp. SBUX, +0.06% was in the number two spot with $17.65 billion in U.S. sales.

Read:What McDonald’s can learn from Chick-fil-A and Subway

“If this plays out this way, Chick-fil-A’s 2018 U.S. systemwide sales would easily surpass those of Burger King and Wendy’s,” Kalinowski wrote. Burger King is part of the Restaurant Brands International Inc. QSR, +1.57% portfolio.

In notes published earlier this year, Kalinowski highlighted just how large McDonald’s chicken business is, with the company selling more pounds of chicken than beef in 2011.

But Chick-fil-A has plenty of room to grow. For example, as of March 2018 Chick-fil-A only had 11 restaurants in New York, a state with more than 19 million residents, according to Kalinowski. Other states, including Massachusetts, Ohio and New Jersey, could also add locations, and market share at other chains’ expense.

See:McDonald’s to trim antibiotics from its beef

Wendy’s Co. WEN, +0.90% , and the chicken sandwich business it has built, could also be in the crosshairs.

“For years – decades – Wendy’s has received credit from the consumer for offering chicken sandwiches that are higher in quality than those that can be found amongst typical quick-service fare,” Kalinowski wrote. But now, Chick-fil-A is “found much more readily.”

There have been reports that Subway’s traffic has dropped by a quarter over the past five years.

Taco Bell, which was number four in U.S. systemwide sales in 2017, could grow by 5.5% to about $10.33 billion this year, according to Kalinowski. Taco Bell is a Yum Brands Inc. YUM, +1.78% chain.

Don’t miss:Burger King trolls McDonald’s with penny Whoppers to promote new app

Here's how to find the best credit card for your financial situation

“In any case, the odds are very good that Chick-fil-A takes the #3 position in 2019, even if it doesn’t quite get there in 2018,” the Kalinowski note said.

Overall, SunTrust Robinson Humphrey analysts are bullish on the restaurant industry, with growth decelerating to 5.6% in November, but up 7.3% in October and reaching a peak of 9.6% growth in July.

Still, restaurants including Chick-fil-A are also facing competition from the nation’s couches.

“For a variety of reasons — streaming media, working from home, the need to find comfort and shelter from the maddening crowd, or practicing Hygge, the Danish art of coziness — U.S. consumers are staying home,” wrote NPD Group in a note last week.

However, more people are eating restaurant meals at home, accounting for 32% of traffic for the year ending September 2018, according to NPD. This also highlights the competition among restaurant chains to beef up their delivery capabilities.