I think she will always be known as Aishwarya Rai, whether she changes her name or not. Also, I am sure she will want the illustrious name Bachan, so maybe it will be A. Rai Bachan.... quite a mouthful, but better than nothing. π
Also, for professional reasons there are advatgages in changing as well as advantages in not changing her name... π
I know to me, she will always be Aishwarya Rai, marriage or no marriage - nothing will change that! π³