1) Long term care: This couple can't qualify for Medicaid; any unexpected sickness leads to long term care will "eat up" all savings; the current premium for a couple is about $600/month in CA
2) Life insurance: It could be term or Whole; in case there is accident, your kids are protected.
3) No mortgage; but still need auto insurance, home insurance, it takes at least a few hundred dollars
3) Inflation: It needs $10,000/mon in today's money