Should Aunt May die for good?

[Kanos]

Mephisto wasn't interested in Mayday, he was interested in the second child Peter and MJ would have had if they had remained married. That daughter is implied to be the one that will defeat him in the future, which is elaborated on in the closing pages of Spencer's run

Norman would have been just as interested in May's corpse as he would have been with her alive, given she has Peter's unique DNA, living or dead. Remember, Norman ordered Mayday to be cloned at an infant age in the Spider-Girl timeline.

The fact that the baby was stillborn doesn't change the fact that it's weird not to mention it. Also, the dialogue with Kurt in Hunted hints that Peter never had children and doesn't know what it's like to lose a child, so he tried to stop Kurt. The same can be said for Peter's monologue in ASM #60. The story itself does not say anything about what kind of child it is. I'm pretty sure it's Mayday and not Annie because she had a Ben costume and canon hair, the only difference is her red hair, but 616 and MC2 are different in some places (the real May died in ASM #400) so it's nothing strange. If Norman had kidnapped the dead child of Peter and MJ, then "good Norman" would have told them about it, but this did not happen

Well it could be retconned that the baby is actually alive, by Mysterio or some other way but it's because May would be the one to finally defeat him and end his reign forever

Mysterio works for Mephisto, he has no reason to save Peter's daughter. At this point, it looks like Peter and MJ erased their daughter from the timeline, it was Mephisto's plan because Mayday (since the girl in ASM #74 was in a Ben costume with Mayday hair) would end his reign.