OLiWW:
Unless I am very much mistaken, the XLA programme is an ITC operation. As such the number of passengers is largely irrelevant, since the tour operators contract the aircraft, and may, probably for reasons of trimming available capacity in an indifferent economy, or getting a better seat deal elsewhere decide to ditch XLA.
Same goes for the possible loss of other capacity. it may in part be replaced by non based aircraft, but frankly, mid July 2008 is hardly soon enough to establish what will or will not be operating when May 2009 rolls around.