Question: Do we know that Michael is dead for sure? It seems way too abrupt, against character and anti-climactic for him to have died in the manner alluded to in the film. Or should we assume that not seeing his corpse or hearing 100% confirmation of his death means he might still be alive?
Question: If Amelia had David towards the end of the 21st century during her reign, how is it possible that Viktor would be suspicious of her whereabouts and send Semira to find her?
Answer: Amelia was a Vampire Elder. She had responsibilities to the coven, to be gone for days or weeks would be normal, but months. Viktor had a suspicious nature. After discovering his daughter's affair with Lucian and the rebellion of the Lycans, he probably feared another betrayal.
Chosen answer: Selena herself said, that Michael was dead. The actor who played him really didn't want to return to the role.