Testing isn't a strictly manual process. You may be writing auto tests, you may be writing tools, you may be branching out into general uptime maintenance. You may even be programming features. All that's gonna depend on what orgs you join and what you are prepared to bring to the table.
Also worth considering the impact on AI in the field. Some orgs are gonna nix QA entirely and rely on AI to generate tests. Others are gonna move more toward TDD with AI using the manually created tests as a guide for the development of features. Still others are just gonna want some assurance that the AI puked up slop that kinda works.
I'm currently a SWE, but I know several people (many who make more than me) who've successfully pivoted into SDET roles and love what they do.