>One practical disadvantage compared to Linux is that it's not GPL, so if Google uses it to make a mainstream mobile phone operating system, other vendors won't

>One practical disadvantage compared to Linux is that it's not GPL, so if Google uses it to make a mainstream mobile phone operating system, other vendors won't be compelled to release their kernel sources like they are with Android today, which means a Fuchsia equivalent to LineageOS might not support as many devices. I would disagree. With the introduction of Android 8 and Project Treble, as long as the userspace OS changes adhere to the HAL contracts, updating to a new OS version should will be considerably easier because there is no need to modify the kernel. According to the Project Treble lead you can even place AOSP userspace on any Project Treble phone and it would work.