For how long will the US be able to borrow money through the sale of Treasury Bonds in your opinion?

The printing presses are already running. The money supply has already been inflated -- about 200% so far. Foreign investors are already cutting back on purchases of US treasuries, especially longer terms. This is a debt-collapse Depression (aka "balance sheet depression"). And so far Congress and the Federal Reserve & Treasury are doing exactly what will make things "worser longer."