The Flash Season 5 Finale: What Does The Ending Really Mean?

9. What Happens?

Picking up where last week's episode left off, 'Legacy' opened with Ralph elongating himself in harm's way to protect Cicada's dagger and allow it to remain intact. Though he was temporarily incapacitated, his selfless act eventually allowed Team Flash to deduce Thawne's plan - leaving them with a troubling ultimatum: Protect the dagger and let Cicada slay thousands of metahumans, or destroy it and allow Thawne to go free in the future.

Nora successfully managed to convince the present-day Grace to take the cure but, given that the dagger was in the near vicinity, it didn't fully work. Thus, despite her best attempts to save the metahuman population and the dagger, the latter had to be destroyed (which also destroyed future Grace) - a decision that did indeed free Thawne.

However, following a showdown in the future with the Reverse-Flash, the team discovered that the changes in the timeline were more significant than any of them thought and, as a new timeline was beginning to take form, Nora was erased from existence.

This was a major shock, no doubt, but it wasn't the only change to the timeline (or the show)...