So, one bizarre thing the Apple Watch could enable is... does anyone besides me remember the Sony PocketStation?
It was basically a memory card for a PlayStation that had a display and buttons on it. A compatible PlayStation game could, alongside its save data, write mini-applications to it, that integrated with the PSX game in some way. Like, "Final Fantasy 8" had a "Chocobo World" game you could play on-the-go, and doing so would level up a summon spell in the main game.
(I am one of the crazy people who imported a PocketStation from Japan to use with my PlayStation. I still have it somewhere.)
Anyhow, the Apple Watch could run PocketStation games alongside iOS ports of the original PSX games. That wouldn't actually be completely stupid (though buying an Apple Watch just for that reason would be).