They did start encrypting the firmware of their latest devices. I noted that the firmware images for Forerunner 55, 945 and 955 were encrypted. Most likely others are as well.
In the live demo I did at Hack in the Box a couple of days ago (slides available [0]) I've shown how to exploit one of the vulnerabilities to read the memory of the Forerunner 55, making it possible to dump the firmware unencrypted. The CIQ demo app is also on our GitHub repo [1].