This is yet another idea for implementing larger worlds on the consoles, but it is more for the online community, and I felt that it was deserving of its own thread as being disjoint from the other suggestions.
Let me preface this first by listing somethings that I personally don't like about online play in general:
The world size feels too confined/small for me to share my world with another person in general.
The host ultimately controls the map, and the player settings.
Resources have to be shared between players from a common world.
So, I was thinking to myself... what if Hosts of their own world had some way to link their world to another Player's Hosted world so that each could travel between one world and the next.
Then each host could 'serve' their own (hosted) world, and play in a different world entirely (as client side). Each world would have it's own set of Host Options as determined by that map's owner/host.
I was originally thinking of just aligning them geographically in a grid format, but thought that something less complicated and much more flexible would work better. Such as a World Portal (maybe out of Diamond/Gold blocks that takes you to a dropdown list of available worlds (and their owners) that you can (have access to) visit.
Neighborhoods would be first divided into Survival Only : Creative Only : Survival/Creative Hybrid
Neighborhoods could further be divided into : Communal or Private
A Communal Neighborhood is open to multiple online players/games/etc.
A Private Neighborhood might be restricted in number of Worlds, specific Player Worlds Allowed, and/or Specific Player Groups might be further restricted by Player.
Neighborhoods would then be divided into Friends Only : Friends of Friends allowed.
In the Friends Only Neighborhood, a player can only go to another neighborhood owned by a Host that they were have listed as a Friend, and only their Friends can join their world.
In the Friends of Friends allowed, Neighborhood World access extends to and is extended to Friends of Friends
Additional Host controls might include:
Allow importing resources
Allow exporting resources
Player Bar Access Form World List
Other Online Players may join into the individual worlds that are in neighborhoods without having to be hosts, but they will only be able to travel to worlds as their Friend or Friend of Friend restrictions allow for that neighborhood.
If Exporting Resources is not allowed from a world, and non-renewable blocks/items collected from a world (not through trades) could be saved to a 'host chest' and stripped from the non-host player upon their leaving or the game unloading.
If a game unloads while other players are still active in it, those players will immediately be taken to the World Portal Screen to select a new world to go to, unless there are no viable worlds to select (if they aren't hosting one of the worlds), in which case, their player information will save locally on their console based on the Neighborhood ID/Player Game Tag to include last visited world, inventory, etc. It is more easier and more efficient for each player's console to keep track of their own player information than it is to try and keep all that information with any one of several Game data that may or may not be available for reading/writing at any given moment, and allows for better flexibility for staying in the MC Neighborhood if their joined World disconnects.