There's an extra qualifier here, where are there Software Engineers past 40s that started in their 30s. I'd don't see many, if at all, that are basically at entry level and end up doing PM/TPM work (not that it's not important, but not worth degree for!)
IMO aging out only really happens when you rest on your laurels and let your skill set lapse. Also happens at younger ages but we just call that being PIP’d. All my dev friends and I are mid 50s and doing fine not being in management.