Background: I was a software tester for 6.5 years; currently a software engineer, having worked with dedicated testers for about 5 years.

"QA" should exist regardless of whether you think dedicated software testing staff fit into your org. The whole team is responsible for assuring quality.

Dedicated software testers verify that the solution actually does what it's meant to do, and good software testers become deeply knowledgeable about the product and how features interact. They are ultimately a second pair of eyes, and should have a direct line to product owners or customers.

This can't be automated. The ongoing tests for verifying existing features continue to work without regression can and should be automated (throughout the dev process), adding generative AI to the human verification step is a recipe for disaster.