1) Better to leave the reservation as is for now, as a significant schedule change means thevticket could now be refunded in toto.

2) Depending on the amount of the fare, there might be sufficient residual value to the ticket after the change fee. This means a voucher would be issued for the remainder and if MCE was purchased, that too. See http://www.flyertalk.com/forum/ameri...solidated.html

3) Failure to cancel or show means there is no residual value; it's all gone. And any empty seats these days are likely to be filled by standbys, etc.