... The point is, Oblivion really lacked a lot of potential content because of the space taken up by, I believe, voice files.
They still had 552.96 MB of space left on the DVD. The amount of space for the mesh for the huge Cathedral in Bruma? 2,657 KB. Which is the equivalent of 2.59473 MB. That means they could have made 213 new meshes that big if they reuse the same textures.
Meshes are really small space-wise and they re-used a lot of textures for different things in Oblivion. The actual .esm with all of the quests, scripts, NPCs, world-spaces, AI, and everything took up a whopping 264 MB. They could have fit
almost a whole entire new game using the same meshes and textures with the space they had left.
They had the space, they just didn't use it for whatever reason. DVDs can fit 4.7 GB, they used 4.16 with Oblivion. Voice files took up a lot of space, but not the whole disc.
Personally, I think there are going to be a bunch of "voices" in a menu that they'll choose from for more generic NPCs. But then important ones will have a unique voice, but won't say the same stuff everybody else does. That's what they did in Fallout 3. Only thing is I hope we'll be able to talk to NPCs in the next game, unlike all of the Megaton settlers who would talk with each-other about stuff, but not you.
If they use more than one disk, we can get an AWESOME game. Full of content, lore, quests, voice-dialogue, and other things.