GCC is still in the NDK today because some of gnustl's C++11 features were written such that they do not work with Clang (threading and atomics, mostly). Now that libc++ is the best choice of STL, this is no longer blocking, so GCC can be removed.
Handset vendors and, especially, mobile network providers, would rather ship their handsets with proprietary unmodifiable software that they can cram with antifeatures that will be that much harder to detect or remove.
Having said that, the reports I've seen contain scant actual evidence that Google actually plan for Andromeda to replace Android, or even that Andromeda is at all important to Google. I take these reports with a mountain of salt. I remember that the "Pixel 3" was definitely just about to be announced back in late 2016, and was definitely going to be running Andromeda OS.
The OS Fuchsia, including the kernel Magenta, appears to be open source, mostly under BSD 3-clause, with parts of the kernel under MIT and similar licenses.
Open sourcing the product will help the competition to catch up quickly, all they have to do is take googles product and change its look. The next half is infrastructure, which companies like Microsoft, facebook, amazon, alibaba all have. Plus services like AWS will help future version of dropbox & netflix.
A good example of that is Visual code. I am sure some at github (atom's paprent) is pissed.
There's a ton of good reasons to replace Android beyond licensing. Security being the largest one. Fuchsia is designed with security in mind from the ground up, Android arguably is not (at least not from the sense of what is considered security today).
https://android.googlesource.com/platform/ndk/+/master/docs/...
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Remove GCC
GCC is still in the NDK today because some of gnustl's C++11 features were written such that they do not work with Clang (threading and atomics, mostly). Now that libc++ is the best choice of STL, this is no longer blocking, so GCC can be removed.
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