Old Platinum  
… and so she kept repeating, Chimicerry and cherrychanga and chimicherry and cherrychanga…
 

 
There was a pic on mlpforums.com of Rarity at the age of Granny Smith, and she was old and sickly, sitting in her boutique.
 

 
I didnt like the picture, I had a feeling that her old age should look different. If she keeps going the way she has been till now in the cartoon, by that time she will obviously be one of the most famous fashion designers of Equestria, a well-respected critic and academic lecturer. Known as Lady Old Platinum Rarity. Has not sewn any dresses for years any more fashion shows being too stressful and quick for her already. But her articles and critics can often be read from the most exclusive magazines and she can often be seen beside catwalks as one of the jury members.
 

 
And memories. Obviously she as an artist, working mentally, will have brilliant memory. She can make ponies laugh for hours telling them about the funniest things of her life, but also about the backstage of high society and fashion.
 
Ponies by me