The "no mod support" is being said my the doomsday (no pun intended) naysers on the forum. Just stupid "ohh thing suck and there's nothing we can do" talk (on the other hand, you're making your own game, kudos!
The only reason there would be no mod support is if it's not out for PC, and if there was no mod support, who cares? D3 already HAS mod support and the engine is GPL. Just rig the engine to support the content file system (ie pk4, whatever they use).
It's not like they're remaking the game in a whole new engine, they're updating the old stuff. Odds are it will still be pk4/zip files, uncompressed textures, openable .map files, etc. Maybe no built in tools (all most people did was complain about them, except me, I enjoy them immensely, but why support them now?). If they put so much resources in to remake every model, texture, SFX, particle, map file, etc. and changed the whole file system then they put more effort in to it then I would of and who could blame them for locking stuff off. It would e a 2012 game and, in general, modders did nothing but complain about D3's modding capabilities.
IMHO this could be done (*IF* it's on PC) just so they support Vista/7/8. XP is officially dead and their second major franchise has no official modern OS support. Wolfenstien has the one released several years ago with Vista support. Quake has Live. Rage has XP & Vista/7. Doom has XP & 2k.