Seriously, the only thing needed is a promotor that can provide anything they need, no matter where it is in the world...
In 2005 MK played in South Africa, India, Arabs Emirates, Australia and New Zealand. Why? Because there were promoters paying them enough to make it possible for the band to travel, stay etc etc.
The 2001 tour by South America was possible because some promoters worked together in gather dates in countries next to each other, and they played in Mexico, Argentina, Uruguay and Brazil.
I'm sure that if South American promotors suggest again the band to come back and they paid for the expenses that need to be covered by such a tour, they will back.