It was always going to happen, the only question was when. A range of third-party services have popped up over the last couple of years offering the ability to cut and upload highlights of livestreams and Twitch broadcasts.
It was the kind of functionality that Twitch should have implemented natively. As of this morning, they have.
But with Twitch including the feature natively, those sites are about to take a massive hit. It remains to be seen how well Twitch's integration will work, however, with Clips not yet available for all users.
"At launch, Clips is available to a portion of users on Partnered channels," a support page says. Update: Twitch has got in touch to clarify that Clips are 30 seconds long, with Twitch capturing the 25 seceonds prior and 5 seconds after the Clips button is pressed.
But those third-party sites will survive in the near-term, until Twitch makes Clips more widely available. I couldn't find any channels or streamers this morning where the option was available, although that could change over the next 24 to 48 hours.