How long do hybrid mattresses last?

Specialist-community threads on r/Mattress repeatedly note that cheaper foams break down and develop sagging or body impressions within months to a few years, while better-built hybrids hold their shape for several years. Reviewers across brands recommend rotating the mattress and using a protector, and they treat long warranties (10-year to 'forever') as only as good as the company's actual return and claims process.