The largest cosmic structures in the universe don't really exist (forbes.com)

> The struggle between gravitational attraction and the expansion of the Universe actually had its end determined some six billion years ago, when dark energy became the dominant factor in our Universe. At that point, any objects that weren’t already gravitationally bound to one another never would become so

This is assuming gravity won't become the dominant force again billions of years from now. We don't know whether or not dark energy is uniformly distributed in the Universe -- if it isn't, gravity could win again one day!