Should retired people pay off their mortgage?

Retirement mortgage payments can be problematic when investment returns are variable, causing problems paying a mortgage or uneasiness regarding a large amount of debt during a market downturn.
Therefore, the next step would be to take out a mortgage and invest the proceeds in securities that should outperform the after-tax mortgage cost, improving your net worth in the long run and increasing your cash flow in the short run.
Further, investments like mutual funds and exchange-traded funds (ETF) can be easily liquidated and sold piecemeal to meet additional spending needs.