Dark matter just makes voids more isolated from each other. Our void is still within the greater Laniakea Supercluster, but our immediate area is very sparse. The only galactic merger that the Milky Way will experience is with Andromeda in 1.5 billion years, and maybe with Traingulum a bit after. But there will be a ton happening in the Virgo Cluster next door as those galaxies are all close enough to each other that gravity is the predominant force in the region. But the galaxies in the middle of the cluster will gather towards their gravitational center, while the galaxies at the periphery of the cluster will form a “shell” of sorts. Voids are just the bubbles that remain from the gathering of clusters.