Future versions of Apple Watch may have buttons that are not physically pressed but, on the contrary, use a Taptic Engine to generate tactile feedback, according to Fast Company.
Apple should continue to use a two-button configuration with a Digital Crown and a side key, but it will not be the traditional physical key.
What is described by Fast Company is practically a key similar to what Apple introduced with iPhone 7 and iPhone 7 Plus in place of the traditional Home key? These devices and the subsequent ones except for iPhone X provide tactile feedback thanks to the Taptic Engine, which mimics just the touch of a button. Apple also used similar technology for the MacBook and MacBook Pro trackpads.
Solid-state keys would improve the water resistance of smartwatches and require less space, for the benefit of a larger battery or the insertion of new components. According to the Fast Company source, Apple is also thinking of using the new keys as sensors to record health-related data, such as heartbeat.
An Apple Watch with such novelty could arrive also in the second half of 2018, but it is the first rumor, that as such must be taken with the right precautions.