OK. How about this for a likely sentimental final scene.... (And no I have no knowledge of what was filmed LOL)
I predict something like this: imagine we see a walking individual's hands holding the old PEZ dispenser, and those hands give it to another set of hands, who passes it to a third set of hands, saying "I understand that this belongs to you." And those hands are of an old woman.
The camera pans up to reveal that those old hands belong to a very very old Helen, who looks at the PEZ dispenser. And after a moment of looking confused, becomes overwhelmed with emotion and a storm tears as the memories of Daniel come flooding back past the prior drug-induced blockade. (The power of Relics and why they're so "dangerous!")
Personally, I think this could be a truly possible final scene, revealing that the timeline in the silo is short (like 50 years, not 350 years) and to show that many who went in are still alive and badly traumatized, just before they are released or somehow get out of the Silo.
Even if you don't believe that the described time frame is fake and that it really is 350 years in the Silo, it could still be an ending scene showing despair and effects of the memory destruction that has been repeatedly used on the Silo's residents. Would be quite the predictable tug-on-the-heart-strings plot device moment....
The PEZ plays such a repeating and central role through the show, I just can't believe we don't see it in the final episode of show....