How Low Can U.S. Interest Rates Go?

As coronavirus fears spread, potentially triggering the signal event that ends the seemingly never ending, passive fueled price insensitive and valuation insensitive buying binge, how low can U.S. long-term interest rates go?

U.S. longer-term interest rates seem to already be pricing in a worst case, low growth, low inflation environment forever scenario.

Said another way, maybe the market is not prepared for a different investment landscape developing.