In the remote possibility that it did occur here, we could expect that there would still be plenty of investment possibilities. So unless the corporate and financial sectors' financial structures had become seriously flawed – something of which there is no sign at present – there would be ample scope for monetary policy stimulus to be effective.
In the (even more unlikely) event that that were not enough, a government sector with an exceptionally strong balance sheet would be well-positioned to use fiscal policy to assist the economy, in this extreme situation.