In (at least) North America it's a tradition to induct the very best players of a league who have not been playing for a certain amount of years. All major leagues in North America: NFL, MLB, NBA, and NHL practice this tradition.
Almost all of the athletes who make it to the Hall of Fame have long careers. Furthermore, most these athletes retire either because of injuries and health reasons, or because they pass their prime and are no longer as effective as they used to be. In both these cases, it is improbable for these players to come out of retirement after the minimum inactive period required by their respective league to become eligible for Hall of Fame. This makes it even harder for a Hall of Famer to make a comeback, and frankly I can't think of any player who has done this in recent years. The only players who I think could possibly do this (but don't believe they'll do) are Chris Pronger, and maybe Brett Favre.
Can a player who's been inducted to the Hall of Fame come out of retirement and start playing in that league again? I personally don't see why the leagues would have problem with this, but if it happens what is the policy of the leagues cited above regarding this situation. Will the athlete's Hall of Fame status be suspended for the time he continues to play?