Breaking into autonomous taxis could drive Tesla shares higher, says one analyst. But a short investor isn't buying that idea.

ARKInvest analyst Tasha Keeney said Friday on CNBC's "Closing Bell" that billionaire investor Ron Baron may not be wrong to believe he can still make 20 times his money on his investments.

"If you look at the opportunity in autonomous cars, which we think is the largest market opportunity Tesla has in front of it, that is quite possible," Keeney said on Friday.

The potential market for autonomous taxi services is actually much larger than the market for manufacturing cars alone, Keeney said. She also thinks Tesla is much further ahead than any traditional automaker in this space. Keeney does not own any shares of Tesla, but ARKInvest owns shares.

She maintains that while Tesla makes a few thousand dollars off each Model 3, it could make more than $10,000 a year in cash off each car if they were used in an autonomous taxi service.

At least one Tesla analyst remains skeptical. Gabe Hoffman of investment firm Candens Capital says such claims about Tesla's upside potential are "absolutely ridiculous."

Tesla is Hoffman's largest short position.

"Tesla already has a $50 billion diluted market cap. To say that it is going to $1 trillion is unbelievable."

Hoffman said recently issued Tesla bonds are "trading in junk territory and will get downgraded to junk."

He also said that the Model 3 will be a "complete disaster" both in quality and safety, and that autonomous cars are at least 10 years away, based on what he reads from autonomous technology engineers.

Hoffman said Musk is "full of it" on Tesla's timeline for autonomous cars.

"Elon Musk makes Donald Trump look like an angel," Hoffman said.

Tesla did not immediately respond to calls for comment.