As much as I'd like to disagree with you here (sincerely hoping that you are right, and I am wrong on this), Rahul Gandhi's presence in Indian politics is the only thorn on BJP's side.
He may be a failed politician but in October 2018, he helped Congress win three crucial states. He also helped Congress win 19% of vote in last election, lets' not forget that. 19% is not a joke for a party that is on the verge of internal mutinies and collapse.
Congress party was full of traitors and closet Sanghis like Sachin Pilot and Jyotiraditya Scindia. The party was already doomed to oblivion; Rahul Gandhi and his mother were the only ones keeping any hopes alive.
If Rahul Gandhi fades away from Indian politics, it will become a cakewalk for BJP to turn India into a Hindu Rashtra. He is really the last piece of resistance. After that, only the Maoists, desh-drohi liberals like me and external agents will remain.