Even if technology changes alot before the plane after 797 arrives, Boeing would still need names for new aircrafts. The way buisness has been going, I doubt Boeing would go bankrupt or simply stop building aircrafts.
One possibility however, is that boeing joins another aircraft manufacturer, and together they come up with new names for their planes. (ex. BC-10, BC-20 etc..)
"If guns don't kill people, people kill people - does that mean toasters don't toast toast, toast toast toast?"