Daggerfall was a rather large game for its time something like 500 megs so um no that would take up far too much space on the disc.
200 megs.
The problem with this idea implementation wise is that Bethesda lost the source code for Daggerfall. As such, they wouldn't be able to convert Daggerfall so it could run without a DOS emulator. To play Daggerfall in Skyrim, Skyrim would have to emulate DOS. And an emulator is a hell of a lot of work to make.
@Target3, GTA didn't try to incorporate those classic games original code into GTA though. Their pretty simple mechanically and what the dev's most likely did was simply write in their own version.