There is no next Charles Woodson, at least not in the league now. Only CB in recent memory who has done what Woodson did is another Woodson: Rod. Most great CBs go the way of Darrelle Revis and Champ Bailey; once the athleticism is gone, they're career is done. There is no move to safety. Making that move is hard, not many CBs can play both at a high level. Rod and Charles were unique and I don't see another CB in the NFL that will be able to do what they did late in their careers.
IMO, Sherman is a very good CB in a perfect system with the perfect safety playing behind him. Sherman can press and be physical and doesnt really need to cover deep b/c Earl Thomas is the best centerfielder in the NFL. That plays into Sherman's strength (size and strength) and hides his weakness (lack of speed). In Seattle, Sherman is a $10m CB. In GB, he's probably more of a $5m CB. I'll pass on Sherman and his $10m+ salary.