Ian McShane as Blackbeard? Helllll, yeah. Pirates should be genuinely--but performatively--terrifying in the way that Blackbeard was in real life, without relying on "But he's Chinese / inscrutable" stereotypes, which cropped up a bit in the third movie. McShane totally fits the bill. And much more so than Keith Richards, or Bill Nighy (whom I adore, but was totally in camp mode), he could stare down Johnny Depp.