The Astros will move to the A.L. West the year after next. That means they'll leave the N.L. Central with one less team, probably right around the time the Astros stop being a punching bag anyway, so this is fine with me. Fewer teams in the division is usually a good thing, because teams mostly compete against the rest of their division for a playoff spot anyway. The only playoff spot that the Pirates might be less likely to get as a result of this move is the Wild Card (because if the Astros are bad, the entire rest of the division has the same chance of benefiting).
Also, the Astros' departure means the N.L. Central's geographical footprint is a bit smaller, and the Pirates will get to have a couple fewer long flights southwest. They also haven't had much of a rivalry with the Astros, anyway, due mostly to the fact that the Pirates have been terrible since the two teams started being in a division together. Although there's always this.