User blog comment:Justarandomguy/Are the Quarians Doomed also?/@comment-1441235-20120318053505/@comment-1441235-20120320031857

There can't be any rebuilding of the mass relays. The relays work in pairs and to build the corresponding pairs you would need communication between the two teams building them which can't happen because all intergalactic communication was done with the com buoys and mass relays, of which most of the former are gone and all of the latter are obliterated. I'm not even really sure the races had a very thorough understanding of how the relays worked, let alone the knowledge necessary to rebuild them. At this point, with this ending, the ME galaxy is well and truly screwed, in my opinion.