But…why?
The biggest problem is the game itself, you can only see a third of a mile away in vanilla minecraft!
There are 2 issues appart, the first and most important is the size of the file, if done expect no less of a terabyte and to support that you will need a server with some HUGE technical means behind.
The second issue is that most of the map won’t be real, it attempts to convert a sphere into a plane surface meaning that the closer your area is to a pole the bigger it will be in the map.