She died, bro. Her head was chomped clean off. Her torso had no head when it fell, there was a trail of blood (censored as pretty sparkles) as she was falling. The remainder of her body was eaten up when it hit the floor. Madoka and Sayaka saw it happen, pretty sure they wouldn't be as shocked if Mami wasn't completely devoured in front of their eyes. The actual death was off screen because it's still meant to be okay for children to watch.
If Mami is ever brought back, she'll still have the memories of having her head separated from her body in her mind. When you die like that, you don't die instantly, it takes a few seconds before the brain shuts down. In other words, she'll have the memories of feeling her head chomped clean off her body. She was also too surprised to even close her eyes while it happened. Her body wasn't "dead" until her uniform vanished.
She dead, man.
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