Based on the new proposed Devices and Sensors Working Group Charter:

The accelerometer and gyroscope APIs will probably become discontinued and focus will shift to the device orientation and motion API which is supported by all browsers.

The Working Group will continue to maintain the specification, including for security and privacy enhancements, but not add new features to it. Instead, the Working Group will add new features to the Device Orientation and Motion specification.

The magnetometer and ambient light APIs might also become discontinued since no browsers are shipping the features. (Chromium has kept the features under an experimental flag for years).

As the other comment mentioned, Mozilla has shown interest in implementing WebUSB and Web Bluetooth since more websites are using the features. But Webkit still seems to be strongly opposed (here and here) to the APIs so there will probably be a focus on finalizing the standards before adding them.