If AI agents do get better than human SWEs, they'll also get better than their human counterparts at other jobs - including being an entrepreneur.
When people call out the doom of SWE careers at the hands of AI, they seem to think that only SWE careers will be affected, which seems weirdly biased to me. If AI comes for our jobs, it'll come for everyone's jobs. And if that is the case, economics/capitalism as it exists today doesn't make any sense anymore.