Pebble actually has more units moved than any other smart watch at the moment. Samsung is second, followed by various Android Wear companies, and then Apple is last. More than threatened, right now they are completely beaten.

It's really amusing that you actually think that Apple isn't threatened.

Pebble is a competitor (and arguably among the most significant, if not the most significant) in a space which Apple seeks to enter. Of course they're threatened. Otherwise, they wouldn't be removing apps solely because they have the word "pebble" in their metadata.