You can lock in cash flowing assets today yielding 6%+ with very low risk. Think REITs with conservative portfolios and strong balance sheets.

You can lock in today's treasury rates for 30 years by buying a 30Y treasury bond.

So, yes, they will last if you understand where to put your money. The options are extremely numerous and plentiful now in cash flowing assets, and you don't have to deal with the uncertainty of selling off principal in down markets to finance your retirement