Updating or restoring a jailbroken iPhone to iOS 8.4.1 will return the device to stock functionality. In other words, do not update to iOS 8.4.1 if you want to keep your jailbreak. iOS 8.4.1 cannot be jailbroken by TaiG 2.
This means the latest version of iOS that can be jailbroken remains iOS 8.4. Anyone updating to iOS 8.4.1 will gain Apple Music bug fixes and other enhancements, but will lose the ability to jailbreak possibly forever.