Oblivion is the state of being forgotten. If you slip into oblivion after selling one record, then your only hope is becoming a "VH1 one-hit wonder."
Oblivion can also mean "total forgetfulness" — like what patients with dementia or new parents feel. If you find yourself putting the crackers in the fridge and milk in the cupboards, or forgetting your own phone number, you might be experiencing oblivion. Enjoy it while it lasts.