You mean there may not be future legendary collaborators such as Rodgers and Hammerstein or Lennon and McCartney? I have seen some credits where up to four writers are listed. There are still many successful songwriters who never did record. At first I was going to mention Irving Berlin but he DID do some recording although quite seldom. Now retired, Bob McDill penned many great hits for country and some pop artists but to my knowledge never recorded himself. John D. Loudermilk also was known for hits covered by various artists even though he did do some recording. My favorite of all his songs "It's My Time" is one he had a minor hit with as a performer. Dylan, Kristofferson, John Denver and Gretchen Peters all made their name with other artists performing their songs prior to branching out to performing themselves.