If you look at all his highlight reels he plays like a safety. I personally think that may be where he ultimately ends up because he has the skills to be an elite safety, but I think he has limitations at CB although he should be able to cover the tall deep threats fairly well like Braylon Edwards (although in many cases, McCourty would be covering those guys and as he shown with his stellar performance against Megatron he is up for the task).
I know saying Dowling might move to safety makes some people's blood boil, but if he can turn into the next Ed Reed why keep him from doing so (although even at safety he may never turn elite or even good because potential and production are not always the same thing).
The one thing is this year, he might stay at CB. With a lost offseason, I don't know if the Pats would want to have Dowling learn a new position right away on top of learning the speed of the NFL and the playbook. He might just be used outside in subpackages this year.