Currently, there is the idea to replace all usages of node_access in general and replace the calls by $entity->access(). See #1947880: Deprecate node_access() in favor of $entity->access() wherever possible for further information.
Unfortunately the patch in the referenced issue can't remove node_access yet because there are still access callback definitions in node_menu() that require node_access. So after the node_menu was improved by using the new routing system, node_access should eventually be removed.