Likely plan B is fork AOSP and crossport security fixes, such features as Google deigns to put in AOSP and so forth. They can do that at any time they choose, may as well wring as much work out of the big G as possible, later is better. Remember their focus is security, it just happens to benefit privacy as well.

Here's hoping they can hang on long enough that there's a viable hardened Linux phone to take the role.