Show Link to Subscribe/Unsubscribe to Nodes in a View
For a single View of non-subscribed nodes:


Using a contextual filter for NIDs, select provide default value by using PHP code.
Then in the PHP code use an EntityFieldQuery to get a listing of all nodes that are subscribable. Save this array of IDs to a variable.
Then use a 2nd EntityFieldQuery to get an array of all subscribed nodes for the active user.
Then subtract the 2 arrays, these are all nodes able to be subscribed to by the user.
use return $subscribable_nodes; to return the nodes as an array to the View.


Your view would contain a node title, and you could rewrite the node title as a link to the subscription url if you want.