Stephen King's IT: What The Ending Really Means

4. IT Is Not Dead

Though he throws himself down the sub-sewer pipe, and seems to be mortally wounded by the Losers Club, it's important to remember that It is an immortal demon. Stabbing him and bludgeoning is not really a viable option for long-term defeat (and as already qualified, it's removing his source of food that really does him in).

So he might have taken a loss in this encounter, but It is not dead. He was simply forced back into the Long Sleep he mentions to the Losers Club that he slips into every 27 years before coming out to feed again.

And as if any further confirmation were needed, in lieu of a post-credits scene, we got a creepy rendition of kids singing "Oranges and Lemons" (because nothing puts the shits up you like a youthful ghostly choir) followed by Pennywise's iconic laugh. He's still there, in other words.