"The only reason WoW is preserved for the future at all with third party vanilla servers is because during the beta they made a mistake and leaked a ton of debugging info and world data early on. Ideally (from the company's perspective), we wouldn't even had that and one of the biggest blockbuster MMOs in history would simply be lost"

I'll disagree with this one right here. I've been part of the wow emulation community at its very early stages and it was in fact some inside info that a few people got. (Angry employees etc you name it) The earliest wow emulator is from late vanilla. The world data also exist on the client side making its easier to use them. Blizzard has found more ways of countering decrypting actual packets from the server to the client but of course as always at some point the c3-c4 packet algorithms are leaked by an unknown source.