SAN FRANCISCO (CBS SF) — The head of a San Francisco taxi company has seen the modern-day writing on the wall and says the taxi industry in its current form may cease to exist within 18 months.

DeSoto Cab Company, one of the city’s oldest, has been operating in San Francisco since the 1930s. CEO Hansu Kim says his industry is hemorrhaging drivers who flee to ridesharing services, using their personal vehicle to offer rides on Uber, Lyft and Sidecar.

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“When I say the taxi industry may not survive 18 months or so, I’m seeing a situation where those who drove a taxi cab in the past are now taking their personal cars and acting like a cab on their own,” said Kim.

A quarter of Kim’s cab drivers have switched to rideshare companies. Among companies across the city, it’s more like a third.

“We cannot compete against an unregulated force,” said Kim, who maintains rideshare drivers aren’t playing by the same rules.

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The California Public Utilities Commission defines rideshare companies as Transportation Network Companies. The CPUC has adopted regulations such as driver background checks, car inspections and a $1 million-per-incident insurance policy for drivers using their own vehicles.

Cab drivers complain the rules don’t go far enough, saying rideshares don’t have to pay the same fees or be specially licensed.

Kim sees more more drivers jumping from the sinking ship that is the cab industry if things don’t change.

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“People are not getting cab drivers’ licenses anymore, because they don’t have to do that anymore,” said Kim. “The concern here is if the driver pool of people who used to drive cabs, it questions if the taxi industry can survive that.”