Meghan Markle has “one arrow left in her quiver” in her apparent bid to maintain “relevance”, according to royal commentator Maureen Callahan. The Duchess of Sussex has maintained a relatively low profile in recent months with public appearances kept to a minimum. Speaking on GBN America, Callahan speculated on how Meghan might go about catapulting herself back into the spotlight if she wishes to do so. “It’s been rumoured for a long time that Meghan might write a memoir”, she said. “There aren’t many things left that Meghan can pull out of her hat in terms of garnering some relevance. “The Ne…