Basically, the only way Nintendo can remove A9LH, is if you are stupid. But since Luma3DS, SaltFW, and ReiNAND all have it on by default, those are completely noob-proof.I think you might have answered my question here actually - so depending on the CFW, it's likely that the CFW will protect the A9LH install. That makes lots of sense. So in theory if Nintendo attempted to remove the modifications the read-only lock in place would halt the upgrade.
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An update running without the protections in place on the CFW - thanks for the good answer.
Corbenik and CakesFW do not have it on by default. But since they are Dev/Poweruser driven CFW's, the devs just assume the end user is smart enough to remember to turn on these protections.

