Apple Glasses will launch by 2020 and will eat into sales of iPhones, Loup Ventures’ Gene Munster said this week.

Munster, who’s widely followed by Apple watchers, said Apple Glasses will be an augmented reality (AR) wearable that would let users view digital content on top of the real world — including information that users currently rely on iPhones to provide.

Munster believes that iPhone growth will peak in fiscal 2019 before beginning a slow decline with the introduction of Apple Glasses.

“We expect iPhone revenue to grow at 15 percent in FY18 (essential the next iPhone cycle) and account for 64% of revenue,” Munster said. “We believe tough comps after the next iPhone cycle will have a negative impact on iPhone growth in FY19, and in FY20 we believe Apple Glasses will start to impact iPhone sales.”

Munster doesn’t explain why sales might drop off, but the reason might be simple. Augmented reality glasses could offer features that are redundant on an iPhone, allowing users to interact with apps right on their faces without having to pull out an iPhone.

Munster said he expects iPhone revenues to begin to sink by about 3-4 percent year-on-year between 2020 and 2022, with unit sales falling up to 2 percent.

Apple Glasses are expected to be the next big product from Apple, at least according to Munster. “In 10 years we expect the iPhone will be around, but be a much smaller part of Apple’s business as Apple Glasses slowly gains market adoption.

Apple has in no way confirmed it’s working on smart glasses, but has discussed how it believes AR will play an important role in the future of technology.