I think byes would be the best solution (over kicking people out of a tournament)

When the deadline hits, the system should:

1. First lower the number of spaces to the lowest possible - so if it was setup as a 32 player tournament, but only 14 players joined - automaticly switch to the 16 player tournament.

2. Then randomly (or I think some would say highest ranked?) pick 2 people to get the automatic byes into the next round.

I think for Fencer, just needs to image a "fake" user called bye who will be inserted into every empty space. This "fake" user automatically "loses" the game which allows the next person to move on. All games are "not counted" and "not rated" - that way the system will move the players on to the next round.