It seems like a foregone conclusion that MLB will be expanding the playoffs to feature 10 teams (5 AL, 5 NL) in the near future. What I don't understand is how they can do so while being fair to all teams involved.

Wether the divisions are eliminated or not, the plan is to have the 4th and 5th best teams in each league compete for the "wild card" spot, rather than simply handing the playoff birth to the 4th team. 

Consider that the two wild cards were to play a one game playoff to decide who makes it to the postseason. First of all, one single game is a very small sample size to use to determine who has the stronger team. Luck could play a big part in determining which team advances, rather than merit. Secondly, in a do or die game, both teams would need to "go all out" with game 7 type strategy. The starting pitcher would have to be your ace, and every pitcher on your roster would have to be made available for as many pitches as necessary to win. The winner of that game would go on to face the ace of the top team in the league with their own ace, used in the one game playoff (and maybe some other pitchers as well), unavailable. That puts them at a serious disadvantage even before the start of the division series. Is that fair to the wild card team? Not in my opinion.

Consider the other possibility: The two wild card teams play a short 3 or 5 game series to determine who advances. Sure, that would take some of the randomness out of the competition and the likelihood of the stronger team winning would be greater. However, while the wild cards are spending several days playing their series, the top three teams, aren't playing. Their pitchers and hitters are sitting around, getting rusty. Is that fair to the teams who earned their playoff births by wining their divisions? Not in my opinion.

No matter what happens with the realignment situation, MLB should strongly consider keeping the current 8 team playoff format. Since, in each league, there are 4 spots in the playoffs, they should be given to the 4 best teams who earn them by winning games throughout the season. Don't give a 5th team a second chance. They'll only end up dragging another team down with them.