Here's what someone from Nvidia had to say:
Source.
Am I misinterpretting it?
Edit: I see now. I think I psoted two different things. One for bandwidth only and the other for space.
In regards to textures Tiled Resources means what id-tech5 did in Rage, Wolfenstein: TNO and The Evil Within did - meaning Megatextures. Of those you only need to load a portion per scene. But these mega-textures are gigantic so even if you load just a tiny bit of these, you'll still need huge amounts of VRAM. But that'll be just a few gigs in stead of a couple of dozends of them.
So if you have a game using a 32 Gig Megatexture (uncompressed), you might just need 2-3 Gigs of VRAM. By the time DX 12 is around, I'd wager it will be more, since quality should improve drastically regarding some pretty ugly low-res textures in Wolfenstein.
EDIT: Btw.: Yeah, as a Nvidia-user, you would need Maxwell to use these, Tiled Resources is in DX 11.2 - meaning you could also use a Radeon HD 7xxx and up which already support DX 11.2.