Actually, the only scenario where I can see Leblanc getting a permanent spot on the roster for next season (emphasis on permanent -- Leblanc can indeed be a good injury call-up, and gain a regular spot THEN, but that's not my point now) is if Eller gets trading for a D-Men (big physical D-Men, basically the guy who'll take Bouillon's spot next season IF THAT GUY ISN'T TINORDI); or, if Cole leaves/retires.
It COULD be somebody else than Eller, but Leblanc is more Eller-like than anybody else on this roster). Trading TP or DD doesn't work, as they are either too different, or just not in the good roster spot. One would think Gionta leaving this team is a distant possibilty as well; then Gallagher takes his spot and Leblanc is next in line for Gallagher's spot.
Armstrong will probably play only one season with this team, but I'm inclined to think that the team wants to get tougher on the fourth line, and Leblanc isn't really an upgrade over Armstrong in this case...
In other words, Leblanc's eventual spot in the roster is closely liked to what will happen regarding Eller, Cole, Gionta and Armstrong. Leblanc plays right wing at the moment, right? Three of those players are also RW's.