Later in the article: "The company has also internally discussed adding biometric sensors to future AirPods, like a heart-rate monitor, to expand its health-related hardware offerings beyond the Apple Watch, another person said."
"Apple Inc. is about to pump up the volume on its audio-device strategy, planning higher-end AirPods, a new HomePod and studio-quality over-ear headphones for as early as next year, according to people familiar with the matter.Apple to Unveil High-End AirPods, Over-Ear Headphones For 2019 -- Bloomberg
The Cupertino, California-based company is working on new AirPods with noise-cancellation and water resistance, the people said. Apple is trying to increase the range that AirPods can work away from an iPhone or iPad, one of the people said. You won’t be swimming in them though: The water resistance is mainly to protect against rain and perspiration, the people said."