I'm told they won't "wait for stragglers" unless you specifically ask and the answer may still be no. (except the last bus of the night or times when the next bus is severely delayed.)
While it would be nice to call them and cancel just those two Disney bound reservations, there is a chance the entire ressie could be screwed up so my feeling for today is the same as the previous poster, just don't put the tags on the affected luggage.
Disney hints:
http://members.aol.com/ajaynejr/disney.htm
Oops! A slight risk! There has been at least one recorded instance when untagged baggage was summarily taken out of the airport, onto DME trucks, and to the resort because the guest's name was on Disney's DME list. It happened late at night when lists are scrutinized more carefully to avoid closing down before the last guests have arrived and to help make baggage magically appear in rooms more quickly.