"Nearly 35 years after 1984, it's time for Apple to redefine its core," HSBC wrote in a note published Tuesday. "Apple's iconic hardware unit growth is broadly over for now. ... What has made the success of Apple, a concentrated portfolio of highly desirable (and pricy) products is now facing the reality of market saturation."

Apple's iPhone segment, which still accounts for more than 60 percent of Apple's total revenue, is waning. The company has recently upgraded legacy product lines like the Mac and iPad, and it's struck modest gold with some of the latest accessories . But it needs a new high-priced, high-margin product if it wants to sustain its impressive rate of growth, the HSBC analysts said.

Apple needs a new product, as iPhone sales slow and drag the company's stock lower , and it has three possible winners in the pipeline already, according to HSBC analysts.

But HSBC outlined a path for future success, based on segments Apple already has under production: augmented reality glasses, transportation and autonomous driving, and health services.

Apple smart glasses could be the first practical, daily application of augmented reality, HSBC said, and launch as early as 2020, according to Bloomberg. The glasses would overlay virtual information on real-world environments, hovering weather updates or news alerts on the user's field of vision, for example. Google and other companies have attempted AR glasses for daily use, but have yet to perfect the design. Apple is taking longer to roll out its inaugural version, fueling hopes the company could finally get it right. Apple CEO Tim Cook has repeatedly praised the promise of AR, calling it as transformative as the original iPhone.

The autonomous driving space, though crowded by heavyweights like Tesla and Waymo, is ripe for a reliable operating system, HSBC said. Apple originally envisioned building a full car, but pivoted to automaker partnerships and building out the software. Apple would have some ground to make up in the space, but a proven sensing system for autonomous vehicles could catapult the company into an entirely new category.

And in consumer health technology, Apple is already showing promise. The health features of Apple's Watch, including a soon-to-be launched EKG monitor, have already eclipsed the incumbent in the wearable fitness tech space, Fitbit. Plus, the company has started working with medical professionals to leverage Watch data for better patient care.

"These applications, especially the latter two could push the company towards a more software-centric strategy compared to the hardware centric business it has developed so far," the analysts said.

The investing firm downgraded the stock to a hold rating and lowered its price target. Shares of Apple fell more than 3 percent in midday trading.