What happened to all the non-Equestrian equine societies (Saddle Arabia and friends)? They’re not like the changelings, dragons, or kirins that presumably went extinct when the magic disappeared. Did they lose their magic, too? Did they retain their magic but never explore outside their borders to restore it to the lands formerly occupied by Equestria?
In regards to this, first of all I don’t think that the other species went extinct. They were too intelligent to completely die out due to the loss of magic in the Kingdom of Equestria. In fact, I think it is very possible that magic continued to exist in these isolated kingdoms even when Equestria itself lost magic. After all, so long as they continued to get along with each other they wouldn’t have lost their own magic. Instead, my theory on what happened to the other magical creatures is that they went into hiding, keeping to themselves for the most part for the last thousand years. And it makes sense, as that is exactly what the different pony species did as well. As for the outlying cities that were controlled by ponies, who knows. Some of them would have disappeared when Equestria lost its magic, though there are likely a few that were far enough away from the borders of Equestria to not be so heavily affected. I think Kludgetown is a good example of this.