Not to pile on Staal, as he's a player I've always respected and enjoyed watching, but his future with Team Canada doesn't look promising if he stays in Carolina. He's probably the one player in the league right now who would benefit the most from a change in scenery. In all honesty I think Hockey Canada has turned the page on him and Jordan.
I personally think Hall has a great shot at making a 2016 WC team (if there is a WC), even without the international experience. That lack of experience most likely cost him a chance at a roster spot in 2014, as compared to, say, Duchene, Hall lacked that experience on international ice and didn't perform very well when he did play at the Worlds in 2013. A 2016 WC would be played on NHL-sized ice, and while the ability to play on the larger ice surface was a key consideration in putting together the 2014 roster (Duchene, Nash), it won't be a significant consideration in 2016. Of course the coaching staff, resulting philosophies, and overall team makeup will have a huge impact on who gets selected and who doesn't.
From the 2014 team we'll almost certainly lose Kunitz (LW), Marleau (LW), Sharp (LW), Nash (RW/LW), and St. Louis (RW). Not to mention Perry, Bergeron, and Carter, whose games may begin deteriorating by that point but will probably be given the benefit of the doubt until then based on past service. At the natural wing position, Hall is clearly our best option right now to fill any of those LW spots, with Stamkos the only "lock" at RW. Hall/Benn will be our best two natural LWers by that point, if they already aren't, and the other guys who'll be fighting for roster spots are largely centermen who can play the wing if necessary (Giroux, Seguin, Couture), have no proven ability to play the wing (Johansen), or are young guys who have some work to do to crack the squad (MacKinnon, Nugent-Hopkins). And of course the Eberle's, O'Reilly's, etc, etc who'll get a good look. All to say, I think Hall has a great shot.