It will never happen if they have to recreate the voice assets.
why can't they just reuse the original voices of NV? Not redistributing them of course, but installing the mod you'd point to your totally legit install of NV and the mod would use that?
They can, regardless of what Bethesda says.
Creating a tool that would take assets from a FNV install and repackage them in a format for FO4 would be perfectly legal, as nothing that is copyrighted is being distributed.
Eh... First, "legal" and "EULA compliant" are very different things, and an amateur modding crew ain't gonna take the matter to court. Second, Bethesda has been very
laissez faire about modding, as they should be, but
if they were to start getting hassled by the VA union, for instance, it's not inconceivable they might slam the breaks on things - they wouldn't even have to fight the legality of a repackaging tool, they could just nix the game port altogether on general copyright. I don't expect they would in either case, I imagine they only said no when asked because they were contractually obligated to, but there is a risk.