Is the world right to continue to invest in US Treasuries?

The United States has a structural need to finance its external deficit and external debt. The economic policy conducted by the Trump administration (fiscal deficit at full employment) will worsen the US external deficit and this borrowing requirement. Until 2013, it was central banks that bought US Treasuries and thereby financed the US external deficit. But that has not been the case since 2014, since central banks' foreign exchange reserves have been declining since then. So p rivate investors must now finance the United States’ external deficit, which they are doing by buying US Treasury bonds even when the y are concerned about the US economy and they become sellers of US equities . Will private investors in OECD and emerging countries continue to buy Treasuries? An end to these purchases would cause a serious financial crisis in the United States (need to reduce domestic demand to eliminate the externa l deficit, and therefore a marked depreciation of the dollar, a sharp rise in dollar i nterest rates ). In 2019, the United States will no longer ensure its fiscal or external solvency, but will this be sufficient to discourage investors when there is no credible substitute for US Treasuries?