Seven Was Held Together by Wires and Glue
Had her Borg implants failed, she would have regressed to the child she was at assimilation. She would have screamed maniacally, curled up into a foetal position and rocked back and forth begging for her mommy.
The Seven of Nine we know and love was an amalgamation of cybernetic technology and perceived social norms. Without the Borg implants, she's a terrified vegetable.