This may just be one of the best episodes ever! Sourcing it from episode 1 was a great idea and it was a very relateable story. Another brilliant Larson episode.
Currently a three-way tie between Slice of Life, Tanks for the Memories, and Make Friends but Keep Discord for me. I'll probably make up my mind when the season's finished.
I think the fandom will still go on for a long time yet. I think a lot of people will still make lots of fanfiction, animation and art to fill the hole left by the show.
The franchises that have been around a very long time have had plenty of time to spawn massive fandoms (Doctor Who, Star Wars, etc). The MLP fandom in comparison is almost comparable in numbers after only five years.