I was playing the Xbox edition of Minecraft, and i was disapointed that you could not have an infinite world, and i now understand why. I was thinking, what if when you get to the "end" of the world, if you travel out far enough into the ocean, you get a message saying "travel to new world?" and if you say yes it loads a completely new world, taking you out of the previous one and putting you on the edge of the new one, with all your items and the ability to travel back and forth. Just an idea.
Instead of having this option, they could just alter the way it loads from chunks to chunks and, saves. So you could have multiple saved areas in one file.
+ the PC is elder than the Xbox.