I'd say that Clara is already a recurring companion. She doesn't live in the TARDIS and travel with the Doctor continuously; she lives at home and leads her normal life, and the Doctor occasionally drops by to whisk her off on an adventure and get her back in time for tea. She's not even a proper companion, since she hasn't committed to the life. She's just a friend.
I mean more in terms of episode appearances. Clara is still a fulltime companion [to us] because she's in every single episode. Same with Amy and Rory. But when she leaves and we've moved on to another companion, I'd like for Clara (or whoever) to still be able to pop up once or twice, much in the way that Martha did.
I think it would also be fitting for Clara as the girl whose story began as a tragedy. We met her in the Asylum; she died. We met her in Victorian London; she died. How great would it be if this one time she was the companion who lived happily ever after? No alternate dimensions. No mind-wipes. Just a normal girl with a normal life who occasionally gets to see her friend the Doctor when he pops into town.