It has been 34 years since the U.S. Treasury last consistently issued a 20-year bond, but they have announced plans to once again bring these bonds to the market. According to an article in FinReg which cited an article By Kate Davidson and Julia-Ambra Verlaine February 5, 2020, The Wall Street Journal, the “Treasury said it plans to issue new 20-year bonds each quarter—in February, May, August and November—and will hold auctions in the third week of the month, the same week as Treasury inflation-protected securities, or TIPS.” They have not yet determined when the first auction will be held or the size of the initial offering.
There are natural buyers of longer-dated instruments, such as corporations, pension funds, insurance companies and banks. However, it is a fallacy that the Treasury has to issue debt to finance its spending. It doesn’t. Treasuries are issued to set interest rates and NOT finance the deficit spending (see Mosler, The Seven Deadly Innocent Frauds of Economic Policy).