For example Mr. House a key major player in Fallout New Vegas who also happened to study at MIT in Fallout 4.
There is no traces of anything related to Mr. House in Fallout 4. No recordings, no pictures, no research notes, nothing.
If Bethesda acknowledged NV they would have made time to put in references to such an important character, I'm sure.
His robco brand doesn't count, by the way.