Firstly, how can we implement it in a way that is both functional and enjoyable for players; secondly, how could we make changes that benefit both survival and adventure maps.
What if villages had a chance to spawn a "Day-Care" in addition to PokeMarts and PokeCenters? That would make effective use of the "Day-Care" NPC and make the villages seem more alive and entice players to go to them as a resource instead of just pillaging and looting them.
At the very least, breeding as it is now doesn't work for adventure maps at all because it requires each player to have their own ranch block. I think if we did go the NPC route to allow any player to use a day-care at a village, ranch blocks should still be available for a player's base because part of the benefit to those is being able to see and interact with the Pokemon while they're in the block.