I make fun of "Tuvix" like a lot of fans do. It's an easy target. But the way the whole situation is never again mentioned in the series is just regrettable. Even episodic Trek makes callbacks to important events and you'd think two valued crewmembers being fused into one sentient entity and then forcibly separated again, killing that new entity and forcing Janeway to make a painful decision would be an event that she'd reflect on in a later episode as a turning point or moment of growth. But nope.
On to the next episode.
On to the next episode.