Facebook has always worked hard in terms product change, even when their product was doing great with no competition in the last 8 odd years. It is sad that instead of focusing on their own product development, the blatantly aped the Snapchat features on all their owned platforms, Facebook, Whatsapp & Instagram.
Mark Zuckerberg was really pissed with the founder of Snapchat, Evan Spiegel for not selling out his company to Facebook, like Whatsapp and Instagram did. This is why the Snapchat like feature release was rolled out exactly when Snapchat's IPO was was around the corner.
What Facebook has ended up doing is introducing people to Snapchat's most unique feature to people who had not heard about it. This will probe people to explore Snapchat and will help them get new installs.
The proof of the pudding is in our own phones, after people are done tinkering with the new feature on Facebook & Whatsapp, you can see users have dried up on stories feature on both the platforms.
The only trump card will be how Instagram stories perform, the stories feature on Instagram was the right fit given the platform was used for sharing visual-only content.
It will be interesting to see what Snapchat does next, your move Evan.