Shigaraki is not dead in the manga. The storyline has many twists and turns, and his character plays a significant role, so his survival adds to the ongoing drama and suspense.
In a fanfic scenario where Naruto consumes the Rumble Rumble fruit, it would be a huge game - changer for him. His chakra nature could potentially be affected, and he might be able to generate electricity from his own chakra. This new power could help him in battles against stronger opponents. He could send out electric waves to disrupt enemy attacks or even paralyze them. Moreover, it could also change his relationships with other characters as they would have to adapt to his new - found abilities.
One possible plot could be that a new character arrives in the Naruto world with the Rumble Rumble Fruit ability. This character could initially be seen as a threat by the Hidden Villages. However, as the story progresses, they team up with Naruto and his friends to fight a common enemy, like a powerful group of rogue ninjas. They use the unique powers of the Rumble Rumble Fruit, which can create and control lightning - like rumbles, to gain an edge in battles.
Super Rumble in stories could be a fictional concept like a magical showdown or a physical fight with high stakes. It's likely a crucial part of the plot that drives the story forward.