There are thirty Major League Baseball teams, of which, twenty-nine of them are located in America, with the sole exception, being Toronto, which is in Canada. In the history of the MLB there has never been a team in Mexico, and the only other city outside of America, that has ever had a MLB team, was Montreal whose team was moved to Washington, DC in 2005. The biggest event of the MLB season is when the respective pennant winners take on each other in a best of seven game series, known as the World Series. The problem though, is in all honesty, this World Series isn't really a "world" series, but essentially an American series, with the sole non-American team, being Toronto, even though there are many other countries that do play baseball, other than America.
American baseball has done a fairly good job of being more inclusive, so beginning in 2006 they created something called the World Baseball Classic, which is a baseball tournament involving sixteen different nations that is played during baseball's spring training, but the WBC, for the most part, is really itself just another glorified exhibition, of which, its primary purpose is to increase the viewership and popularity of baseball worldwide, but despite there being a country that is declared the champion of such, that country should not be considered to be a true world champion; in addition to the important fact that MLB consists of teams based in cities that play against each other, and those individual teams are really the foundation of who is or is not the true champion.
The country that takes most seriously baseball other than America, as well as having players that have transferred successfully to America, would be Japan, in which baseball is quite popular in Japan, and their season runs along the same basic timeline as America. It would seem that the first test of who is the real world champion would be a contest between the best team in America v. the best team in Japan. While logically, one would think, the games should be played just after the champion is declared in each of the respective countries, there is an alternative timeframe that the games could be scheduled, which would be during the All-Star break, in which the current All-Star break is four days, specifically, Monday through Thursday.
A good suggestion would be that the current champion's schedule be modified, so as to not have a scheduled game on Sunday nor on Friday of the All-Star break, giving that team a total of six days off, in which, they could then play a best out of five game series with the Japanese champion, of which, the first two games would be held in one country, with a one day break, and then the next three games would be held in the other country, in which the team that wins three games would be declared the "world champion". Sure, this would mean that the current champion would not have a representative at the All-star game, but the All-star game is essentially just an exhibition itself, whereas this international baseball contest would have real meaning for true baseball fans.
Currently, the "world" champion is simply the best in America, why not test their mettle against another country's team and see what happens in a contest of real worth.