Paul Krugman says not to worry about the dollar weakening despite recent challenges to its dominance

• Investors shouldn't worry about the dollar losing its dominance anytime soon, according to Paul Krugman.
• That's despite recent currency challenges from countries like China, Russia, and Brazil.
• "The dollar's dominance isn't under threat. And even if it were, it wouldn't be a big deal," the top economist said Friday.

Investors shouldn't lose sleep over the recent focus on potential threats to the dollar's dominance, according to top economist Paul Krugman.