FSB Moderator, I do not disagree that it is a lot of work to manage (I do not know the logistics it takes to make it happen). However, it would be cool some day if this site did make it work!
Your money would not be tied up that long either. With some sports, like tennis, a Grand Slam event is two weeks long. A golf tournament is only four days.
With team sports, you wouldn't necessarily have to go the whole season. There could be futures lines set right before the NFL playoffs or NBA playoffs begin (to see who would win the East/West Conf or overall title). This would give a small window of betting time (about a week or less). And the time the money would be tied up would not be as long.. for NFL this would be a bit over a month.. for NBA, it would be 2+ months.
To prevent people from having their $0.50 tied up for a month, FSB could limit the betting to people who had a $10.00 minimum bankroll. Or FSB could say that you're only allowed to bet 10% of your bankroll on the Futures events.
FSB already puts limits on the amount you can bet i dont think they'd want to irritate users by putting more restrictions on it, also, they do have a forfeit button! in case you bet on something why would tie your money up for long periods of time