Possible? Yes. Feasible? No.

While it is technically possible, it would demand a ridiculous amount of time and work and I really don't see the point in even doing it to begin with. Large does not equal good. Just Cause 2 showed us that, the world was huge but there was nothing worthwhile in it so what was the point?

No but also Large doesn't mean Bad either , It depends on who will do and how will do and if will be done well , I personally Would love to start playing in a Supersized world m where distances are more realistic and not fake few meters representing some kms ....