Broadly this is right but Expedia holds the financial instrument here - the coupons - and Qatar / BA won't get paid until they are used. Expedia has more powers than anyone else to deny payment for services rendered, and unlike small agencies, they are exempt from airlnes' attempt at recovery via a process known as ADM. Moreover one problem with this specific issue is that Qatar has limited rights to amend the coupon. What should happen is that they are put on the next flight and thus the routing is protected and doesn't change. The problem is that Qatar's local policies almost certainly prevent them from routing via (e.g.) Emirates or Etihad or Cathay since they may get lumped with the bill and not get a recovery from the original ticket. Hence Qatar will say "speak to your travel agent" and the travel agent is paid to resolve it. This will happen eventually but it's not a fast process, usually, so I would not want to be in the OP's place holding an Expedia reservation, it's a bit of a risk frankly.