"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
Apple's $15 Billion Cash Reserve
When asked about Apple's plans, chief financial officer Peter Oppenheimer simply stated that having a few billion on hand helps to fund big projects, though there reportedly had been discussion about buying back shares or issuing dividends to Apple stock holders.
Apple could use the money to make strategic acquisitions. In the recent past, Apple has acquired a number of companies, including PowerSchool, Emagic, Nothing Real, Zayante, and Fingerworks. Apple also has plans to expand into a new campus which could take up to $500 million to fund.