By saying Shane has what it takes to survive, I mainly mean for himself and for Carl/Lori and his way of thinking for most things.
I agree with a lot of what he wanted to do when on the farm i.e. killing that guy.
As duffman has said, Rick has sort of taken on what Shane would do, however, isn't quite to his level yet i.e. that episode with the guy running after them.
I also don't think that he would have done a better job than Rick when it comes to protecting the group, pretty much what duffman said, he only wants what is best for him, Lori/Carl, where as Rick would put his own life at stake in order to protect any member of the group. If he was in charge, I would say that the group would be nowhere as big as what it is currently.
I wonder what the next story arc will be? Any ideas?