What will 49ers do at cornerback after Culliver and Cox departures?

Daily 49ers blog for NBC Bay Area website: Chris Culliver and Perrish Cox, both starters in 2014, will be gone in 2015, so what's the 49ers' plan at cornerback? http://www.nbcbayarea.com/news/sports/Niners-Appear-Thin-at-Cornerback-With-Departure-of-Culliver-Cox-296213391.html