Let's take for example that in our game, we divide our world (1000x1000 tiles) into chunks of 100x100 tiles. Each chunk contains its own npcs, traps, players, items, whatever. Now, there comes to my mind many problems:
Pathfinding: what if an npc at one chunk needs to find a player/npc that is near him but not in the same chunk?
Sight: Npc wants to check if someone is near him, what if the nearest npc/player is like the previous example at other chunk.
I'd like to find a solution where the player doesnt have to see how chunks are loaded and interaction between chunks is possible, but seems hard.
EDIT: what i have in mind is a multiplayer rpg (not as big as a mmo), where the map is divided into chunks. Each chunk would represent maybe a settlement, a portion of a forest, a portion of a hill, etc ... I thought about loading not just the chunk being visited by a player, but its surroundings, so transitions are easier.
I need this organization because i'll have many entities to manage. Maybe in the world map exists 100 cities, and each one contains 10 citizens. If a chunk is visited by a player, i want him to see how each citizen talk, and walk, and live. But a chunk not being visited should be handle differently. Maybe i'll do some checks when the night comes to see what happened there.