Thanks for reaching out. It helps in cases of where the ID service was not able to persist before such as browser to app or with hybrid apps. For example: If I click on a link in a browser that opens the mobile app, it will support tracking across that experience. From my understanding you would need to update both the SDK and JS after the release. A quick reminder these are pre-release notes and are subject to change. Keep an eye on the Release Notes for the most up to date information.