>Worldbuilding thread this
>Worldbuilding thread that.
>Never a World DESTROYING thread.

How does your setting end? Does your god get pissed off and smack the shit out of your universe? Does an evil planet killing entity eat/drink all of reality for lunch? Does your political heads go full retard and unleash the Big red button? Does your population get some horrible disease that wipes out all life?
>Inb4 My setting is foreva tho!
Bullshit Nothing lasts forever. Soon we will all be dust and forgotten memories. If your setting doesn't have that it is unrealistic and therefore immersion breaking and therefore shit.