I was wondering if anybody knows how much Godot can handle the size you get when making an open-world like Minecraft, Far Cry, or Fallout 4.
The real question is: How big can YOU make an open-world game in Godot? xD
I think that's also an answer to the question. :D
There's no size limit apart from the memory space needed to store your world. With procedural generation, Godot (like any other game engine) is able to create endless worlds.
The only limit is the user's memory and how detailed everything will be. There is also the Von Neumann Bottleneck problem where data processing can't keep up because of the Computer's architecture. The only way to solve this is to make a computer that does not use the Von Neumann architecture however this would require many years of development and could have more problems then the meta right now.