Terrorism being on the agenda is sure to prevent Bush from being the 2000 GOP nominee while benefitting McCain.
No way. W. would've undoubtedly shifted to being gung-ho & interventionist rather than the isolationist tone that he struck for most of the campaign, but he was as heavy a favorite for the 2000 nomination as Dole was in 1996, Poppa Bush in 1992 & 1988, & Reagan in 1980. Some truly major incident that personally discredits W. would have to happen to see him lose the nomination to McCain.
EDIT: grammar
I meant that voters would want someone with overseas experience.