The Traveler has been dormant for a very long time. It’s now active. It could just bring back Cayde-6’s ghost. Then, Exos do their thing. Cayde loses some memories but is otherwise back to his post.
To break the fourth wall however, the issue isn’t whether it’s POSSIBLE to bring him back. The real issue is that Nathan Fillion is no longer available to record lines for Cayde-6/7.
I believe in one of Cayde's lore cards he mentions that he doesn't like the number seven and would rather stay dead then go though another painful reboot. Cayde was a friend for a lot of us, but bringing him back I feel will only hurt the story instead of improve it.