In the beginning, there was Rajnikanth the actor. He wasn't the best actor anyone had ever seen, but he was quite okay. His biggest gift was an undeniable screen presence. The man had style to burn, and it shone through even when he had a bit of a paunch, a leather belt that could hide Adnan Sami no matter how you draped it, and dance moves that seemed inspired by epileptic robots.
Somewhere along the way, he figured out what his best attributes where, amped up the style, smoothed out a few rough edges, added comic timing to his arsenal and set out to conquer the world. He became Rajni the star. He managed to do it often enough and consistently well, and the public ate it all up. Hence Rajni the Super Star. Whatever happened after that was just momentum.
The bad news is, I'm not entirely sure he can stop it anymore. In order to ensure box office success, the man ends up having to do a whole bunch of stuff that his age and physique no longer permit him to do. The fight sequences in Sivaji alone should get the editor of the movie a national award. Watching him dance is an almost painful experience. It's like he's come full circle, except the robots no longer have epilepsy, they have arthritis.
When you think about it, not too long ago, one could write roughly the same story about Amitabh Bachchan. If this were the Matrix and AB was Neo, the Oracle might've told him at some point that he needed something, maybe death, to take him to the next level. And so it was, that Mrityudaata proved to be his Mrityudaata. A few more filmmakers nailed that particular coffin in movies like Lal Badshah.
And then the man resurrected himself, french beard and all, and became a bankable star again. So bankable, in fact, that scripts like Cheeni Kum and Nishabd and Ekalavya get written now because there's someone like him to star in them. (I said star in them, mind you, not just act in them. AB is a damn good actor, no doubt. But so are Om Puri and Naseeruddin Shah and Pankaj Kapoor. Would these movies have gotten made with them?)
The bottomline is, Neo woke up from the dead and can now stop bullets in mid-air. So can AB. Rajni on the other hand is still dodging them. Action sequences to the contrary notwithstanding.