Not sure if there really are many Queens, or merely many bodies for one Queen. Or whether this Queen is a high leader or the lowest of slaves. Or whether she's an original feature (perhaps even the incarnation of the originator herself?) or a later addition, possibly an outside intruder who lives in the virtual body of the Collective like a parasite.
But the Borg appear big on self-improvement, and they want to bring the joys of this to everybody through assimilation. It would seem unlikely that they would leave their point of origin untransformed; if anything, it might be the location receiving the most advanced updates and resembling its original form the least.
Having transwarp hubs all over the universe, in other galaxies in addition to the Milky Way, sounds like fun... Granted, the Borg don't yet quite control even this one galaxy, but they don't seem interested in total control anyway. And they do like to overextend themselves, eagerly launching the conquest of fluid space and whatnot. The thing is, though, we never really heard of anything extragalactic in relation to the Borg.