Ending fractional reserve banking would cause the money supply to shrink as loans no longer generated electronic money. But the central bank could reflate the money supply by generating new money and directly giving it to the government to spend into circulation with the effect of lowering existing taxes.

However, ending FRB by itself would only result in banks creating near money alternatives to continue their business model of transforming short term debt into long term loans. So ending fractional reserve banking would have to be part of a larger reform ending the practice of maturity transformation within the entire financial shadow banking industry.