What kills of a generation?

[Opalescence]

G4, well who knows. They look more like ponies than G3.5s but they still don't look much like G1s or G3s.

How long will the G4 fad last? And what will G5 look like?

Discuss

The moment the show gets discontinued we'll lose a lot of kids and a bronies. But in the laters case, it's likely just the secondary fandom that's only into the stuff surrounding the show, like the memes and general plonkery related to it.
I think the toyline will last a little bit longer, but not too much, since I believe it depends too much on the show and it's accuracy to it to sell.