A top electronics analyst has slashed his estimate for the number of iPhone X units Apple will manufacture through the end of 2017.

It's the latest sign that Apple's $999 iPhone X may be difficult to find shortly after it launches on November 3 in 57 countries, including China and the US. Preorders for the device begin October 27.

"While we revise down 2017F iPhone X shipments on TrueDepth Camera production & assembly difficulties, it represents a great challenge for Android camp to replicate," Ming-Chi Kuo, a KGI Securities analyst, wrote in an "Apple Insight" note seen by Business Insider.

Kuo now thinks Apple will ship 30 million to 35 million iPhone X units in 2017, down from his previous estimate of 40 million.

The iPhone X has a complicated 3D camera mounted on its front that Apple calls TrueDepth. It's used to unlock the phone using facial-recognition technology. But there have been several reports that significant production issues with the new camera have led to a bottleneck in iPhone X production.

Kuo wrote that "issues with the production of TrueDepth Camera can potentially be overcome in a few months."

Despite the TrueDepth manufacturing woes, Kuo thinks Android manufacturers won't be able to match the camera's features or functionality for 18 to 30 months, leaving Apple with a strong exclusive feature on high-end smartphones and clearing the way for growth in 2018 and 2019.

There seems to be high demand for the iPhone X — a previous estimate from KGI Securities suggested demand of as many as 50 million units on launch day.

This could cut into sales of the iPhone 8 sales, which Apple announced at the same time as the iPhone X. The iPhone 8 is less expensive has a design similar to previous iPhone models, however, so some customers are likely to hold out for the pricier, more advanced device.

But Kuo doesn't think iPhone 8 sales will suffer that much.

"In light of better-than-expected shipments of iPhone 8 Plus, we see limited downside to our combined shipments estimate for iPhone 8 and 8 Plus," Kuo wrote. "Moreover, we are of the view that even if iPhone 8 shipments forecasts are revised down, the consumer appeal and robust shipments momentum of iPhone X will be unaffected."

Kuo concludes that supply-chain companies with "prominent exposure to iPhone X features" are a good investment. Taiwanese companies that count Apple as a customer that Kuo likes include Hon Hai, Largan, Taiwan Semiconductor, Chunghwa Precision, Tong Hsing, and General Interface Solution.