Notes from Wikiquote
The Swiss author François Bondy attributed a similar quote to Ignazio Silone: This reminded me of what Ignazio Silone said in 1945 soon after he returned to Italy from his Zurich exile: "The Fascism of tomorrow will never say 'I am Fascism.' It will say: 'I am anti-Fascism.'" Alternatively quoted as: When I met him in Geneva on the day of his scheduled return home after the long exile in Switzerland, Silone said abruptly: "If at a future moment fascism will return, it will not be so stupid as to say: 'I am fascism.' It will say: 'I am antifascism.'"
Variants
The Fascists of the future will be the anti-fascists.