Interesting concept and opening but terrible ending. Whoever wrote this ending does not understand how time travel works (well, at least at the level of logical sci-fi).
[SPOILERS]
You either in a perfect loop like Predestination (2014), or if you changed anything in that loop, you would need to consider it as a different parallel world as what happened in the Dark (TV series). You cannot just simply "poof" in one timeline just because someone has changed something. That is a very naive and illogical way to describe time travel, as like those cartoons for kids in the 90s. Based on the Butterfly Effect, if Elias did not trigger the bomb, A LOT of things would have changed, not just the disappearing of Elias himself, but Sarah and her home as well, as many more things...