Pidgeons

I want to propose a possible future mob: the pidgeon.
Each pidgeon spawns with an individual "home" location, but once tamed, the player can assign them a new one instead.
Pidgeons can be carried around, similar to an axolotl in a bucket (perhaps using a new item, the bird cage) and can carry up to two items at a time, one on each leg. Once released, they try to find a way back to their "home" location. That way, they can be used to transport items.

At the time of writing, the only real means of transporting items over a long distance other than taking them yourself is to use minecarts. While this method is very efficient to quickly transport large numbers of items over long distances, it takes much time and resources to use it, especially in survival mode, as rails have to be laid whereever they should go. It also makes them unflexible. Pidgeons, on the other hand, would allow to quickly send items from any spot to any previously assigned spot. The minecart would not lose its importance to the game, as pidgeons are highly ineffective for transporting more than two items (one if it carries a return pidgeon) and cannot be used in automated transport systems.

It would be important for enabling a functional pidgeon transport system that a pidgeon can carry two items at a time. This way, you can return a recieved pidgeon in a cage with the next pidgeon you send to its owner. (If you had to return each recieved pidgeon per minecart or manually, that would kind of defeat its point.)