I'm suggesting a mod.
Really simply, I'm suggesting a mod which either loads you into another world when you go through the edge boundary, or creates much larger worlds and only loads segments of them at a time.
Does not have to be multiplayer compatible, though if someone makes a mod like this I'm sure others would very much want it to be, so I'll suggest giving it a 'readying' system where all players currently in the server have to agree to move over to another segment/world together and an experimental option to load all segments with someone in them at once for those with god computers.
You'd also have to spawn in your current world, either in the center or at the edge, if you died, since you couldn't spawn back home unless in singleplayer (and it'd be really annoying to have to load back into the spawn world constantly, knowing how much death is involved with Terraria)

If you have the ability to somehow choose, even through another mod, which world you get loaded into, or if its a segment and included in the base mod, you could have much larger and more dynamic worlds where you have an island for the jungle, desert, snow, ETC and therefore each biome is the size of an entire world and there'd be more ocean-space. If given vertical compatibility, worlds/segments could be made shorter and there could be entire ones each vertical layer (sky, surface, underground, underworld, potentially separated caverns and space). This would be highly interesting but is not the only goal.

I don't have any way of compensating anyone for the creation of this mod, but rather, I'd like to suggest it in general as an interesting concept for a mod. If something like this already exists, which I doubt for obvious reasons but its possible, please let me know.