It’s a big day in fast-food nation: McDonald’s has launched all-day breakfast.

Sorry, #AllDayBreakfast.

Here’s why they’re doing it (domestic sales are diving). Will it work? Temporarily, yes. The breakfast market is huge because millennials are opting to eat it anytime. But because of this, it’s growing more fractured; niche breakfast establishments can step in and steal some of the consumer base from larger, more corporate entities. Which will happen if McDonald’s doesn’t shake up the template beyond offering food deeper into the day.

Taco Bell’s recent breakfast success is due to one simple truth: hangover food. They’ve gone all in on capitalizing off the millennial Moment Economy, providing food that mirrors what you’d have on “the morning after” – let’s throw some stuff in a waffle and call it a meal. That’s fun and shareable. McDonald’s isn’t brash enough to market its food as hangover food. But maybe there’s a middle ground, a way to show millennials that a McD’s breakfast fix is something to talk about and share.

It’s not off to a good start; the McDonald’s Twitter feed should be FILLED with all-day breakfast fun. Only a few tweets with mostly tame GIFs. That’s not going to retain a millennial audience.