There Was a Way to Save Snape in Harry Potter and Deathly Hallows After All
And it had something to do with Dumbledore — or, to be more precise, with his pet.
There were several times in the Harry Potter franchise when close allies of Albus Dumbledore were targeted by Lord Voldemort's pet snakes. One such time was in Chamber of Secrets, when Harry was attacked by a basilisk and accidentally got injured by one of its poisonous teeth.
Another time was in Deathly Hallows — a much more dramatic scene when Voldermort's snake and horcrux Nagini killed Severus Snape at the dark lord's order.
However, Harry was lucky enough to be saved by Dumbledore's phoenix Fawkes, who cured him with his magical tears. It happened because Fawkes knew that Harry was loyal to Dumbledore. However, in Snape's case, the potions professor's loyalty did not help him to summon Fawkes so he could cure his wounds.
That doesn't sound fair to Snape fans, many of whom still try to get over the death of their favorite characters.
"The books often compare Snape and Harry and it would have been fitting where both of them get saved by Fawkes from a poisonous snake bite cause by Voldemort," Redditor ReasonableTwo4 suggested.
Other people came up with what could work as an explanation. According to them, Fawkes was no longer a savior and a guardian for Dumbledore's allies after the Hogwarts headmaster's death in Half-Blood Prince.
After Dumbledore was killed (notably, by Snape), Fawkes left Hogwarts and apparently became a wild phoenix again. This, combined with what could possibly be bad blood with Snape over the murder of his owner, might have been the reason for Fawkes to simply no longer care.
Another fan argued that "Nagini is a constrictor and does not have a venomous bite", rather biting "the main arteries of his neck and he bleeds out."
Looks like Snape had no chance to survive in the last book, even though there were ways to somehow save him. After all, with the dramatic life the character had, who could have expected his death to be peaceful and not heartbreaking?