Proton is open source, isn't it? I'm sure you can convince it to run a Blizzard game. Not sure about the results though. D3D9 WoW works very, very well under wine-d3d9[0], but D3D9 support was dropped from WoW a long time ago.
Can't say anything about the rest of Blizzard games.
Can't say anything about the rest of Blizzard games.
[0] https://packages.gentoo.org/packages/app-emulation/wine-d3d9