JOHANNESBURG/BENGALURU—Most emerging market currencies will continue to struggle against the mighty dollar over the coming year as the U.S. Federal Reserve finally delivers expected aggressive policy tightening, according to a Reuters poll of FX strategists. Central banks in emerging market economies have been bracing for this for months by hiking their benchmark interest rates. But the actual moment when the Fed delivers half-point rate increases and rapid balance sheet reduction still matters. Minutes from the Fed’s March meeting showed officials had generally agreed to trim the central bank’s balance sheet by $95 billion a month, providing a major boost to the greenback which was already riding high. The latest Reuters poll of over 50 currency strategists showed nearly all developing market currencies would weaken over the coming 12 months. Even currencies which have been dragged higher by the ongoing commodity cycle and their respective central banks’ policy tightening, like the …