Yes,they are going to bring her back
Why do you thing Suzaku told Lelouch to bring Euphemia back?
Apparently,Nunally got some ultra-strong Geass,strong enough to revive people
When her mother died,she tried to revive her,but she failed and now she can't use her legs and her Geass
She is going to revive ALL the people that died in the war,and we will get GOOD END