If all US dollars were converted to bitcoins, the value of the dollar would likely decrease significantly. This is because the supply of bitcoins is limited, so a sudden influx of demand would cause the price to rise. Additionally, the increased demand could strain the existing infrastructure for buying, selling, and storing bitcoins, potentially leading to difficulties for individuals and businesses trying to participate in the market. The long-term effects of such a conversion are uncertain and would depend on many factors, including the state of the global economy and the stability of the bitcoin market.