Was it not obvious to anyone else that if the Pokemon drop to zero motivation, they will leave the gym? And, seeing as Pokemon AUTOMATICALLY lose motivation OVERTIME, it goes to reason that your Pokemon won't be stuck in a gym because they'll lose Motivation and leave it. It may take a day or so, but there is currently (from my understanding) no cap to the amount of Coins you can get from gyms, so the longer they can sit in there, the better.

I believe what this will do for rural players is such: Rural players will now have an abundance of coins to buy useful items (such as Pokeballs) to help make up for the lack of conveninece that players in cities have. In contrast, players in cities will now be the primary purchasers of PokeCoins as they won't get as many as Rural players can. And everyone will be encouraged to regularly interact with gyms to level up their badges so that they can get more items from them.

All that, combined with the new Ingress submission system that has been proving to be a decent success means that we'll get new PokeStops, new Gyms, and everyone will have a lot more fun overall.