In the span of about 60 years, the NCAA men's basketball tournament field has expanded several times. It began with eight teams in 1939 and has grown at a healthy rate since, reaching 64 teams in 1985 and its current format of 68 teams in 2011.

Major League Baseball has expanded its postseason twice since the 1994 strike season, with four wild-card teams now playing in two winner-take-all games to earn spots in the Division Series.

The NBA and NHL playoffs seemingly stretch from spring into summer, and the NFL is on the verge of expanding its postseason (again) from 12 to 14 teams by 2015.

As college football embarks on its first season with a four-team playoff -- a seismic change I never thought I'd see in my lifetime -- fans from coast to coast are already wondering when it will expand. If college football is to follow the example set by other sports, it seems only a matter of time before the four-team playoff grows to eight or 12 or 16.

"It's never going to stay at four," said one FBS head coach. "It's going to expand because they'll never keep everybody happy."

How soon can we expect such growth to occur?

The first time Alabama gets left out of the field?

Or when a politician from Idaho or Utah steps in front of Congress and complains about Boise State or BYU or some other team from a non-power conference being unfairly left out of the four-team field?

A few coaches, like Notre Dame's Brian Kelly and Stanford's David Shaw, believe a four-team playoff is only the starting point.

"I don't know that four is where we're going to finish this thing," Kelly said last year. "I think it's a great entry into where we want to go. Moving forward, I think the focus will be on whether it's eight or 16 or whatever the number is."

Added Shaw: "We're not ready for it yet, but I would love to see it at some point go to eight."

For all of its flaws, the much-maligned Bowl Championship Series largely delivered what it was supposed to give us: the top two teams in the country playing for the national championship at season's end. Sure, there were a few bumps along the way. Nebraska, a 62-36 loser in its final regular-season game, still played in the 2002 BCS National Championship Game and was crushed by Miami; undefeated Auburn was squeezed out of the 2005 title game. But the BCS actually got it right most of the time.

Now, a 13-member selection committee will choose the four best teams to play in two semifinals and a national championship game. Expanding the field from two to four won't necessarily make their jobs any easier; in a lot of ways it's actually going to be twice as hard. What if there are only one or two undefeated teams and seven one-loss squads? How can a committee really weigh which teams are most deserving?

College Football Playoff executive director Bill Hancock insists the playoff won't expand anytime soon. Each of the 10 FBS conference commissioners and Notre Dame athletic director Jack Swarbrick signed a 12-year agreement to keep the playoff at four teams through the 2026 season. It took several years to persuade BCS holdouts like Big Ten commissioner Jim Delany that a playoff was actually a good thing -- remember when SEC commissioner Mike Slive's "plus-one" model fell on deaf ears?