What is the idea behind SQA?
If SQA stands for “Software Quality Assurance”, then I hardly find a project team member not under that cap —in a team with agile principles, values and practices, that is.
If SQA stands for “testing” (validation and verification testing, for functional/integration/acceptance testing purposes) then I think the old practice of having a different set of professionals doing destructive testing still is a good advice (if finding bugs is the goal).
Unit testing for Test-driven design is for developers (constructive mindset), validation and verification for functional/integration/acceptance testing purposes is for testers (destructive mindset). Hence, testers’ role does not change very much while adopting agile methods.
Moreover, making really sure quality is in there implies something greater than thinking SQA as a role some people have in a software project.