I know that when "Infinite Tsukuyomi" is cast, each and every person having chakra is trapped into a dream world.
What happens to them if the person who controls the dream dies?
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TL;DR: The Genjutsu (the dream world) would end and everyone would return to reality.
I'm not an expert in Naruto lore but having read some of the manga and watched the anime:
Genjutsu is created when a ninja controls the chakra flow of the opponent's cerebral nervous system, thereby affecting their five senses.
Therfore, if the ninja no longer controlled the chakra flow in the opponent, the brain would no longer be affected. Ergo, any illusion created by the Genjutsu would end.
Genjutsu attacks usually require a lot of skill, and, if performed incorrectly, will not work... Genjutsu is most often used by ninja with very precise chakra control and very high intelligence.
The Infinite Tsukuyomi technique originates from the Ten-Tailed Beast who is considered the incarnation of the origin of chakra. In other words, it has the potential of having infinite chakra by absorbing it from its victims by use of the God: Nativity of a World of Trees technique. Note that for the Infinite Tsukuyomi technique to be infinite would require other techniques.
So summing up, if the flow of chakra to all victims under the effects of the illusion were broken, there would be no other reason for them to remain under the Genjutsu.
But don't quote me on this.