So in order to switch from ARM to RISC-V, Huawei essentially has to abandon Android including all forks and redesign an OS around RISC-V, right?
Nope. Android is open source. Huawei can make changes to the source code to allow its version of Android to run on top of whatever SOC it produces. Android is based on Linux and Linux has been ported to all kinds of CPU's, including Loongson (MIPS-based ISA).
Nope. Probably no. Pointless because Android apps wouldn't support it due to limited market (think Windows Phone)Do you know the answer to this question?
"Is it impossible, illegal, or both for Huawei to take the ARMv8 that they have a permanent license to and improve it themselves for future upgrades?"