The VHS tapes will last longer than the DVDs.
The longevity of DAT (audio) tapes is another bete-noir of mine - and others:
Archivists Warn: Don't Depend on Digital Tape
One snippet from the 1995 article relates to CD-R
Nichols, who has started a new company that specializes in audio restoration, said he's been working with Kodak's CD-R, which, through accelerated aging tests, is now said to have an archival life of 267 years.