Staal has made it clear that he prefers playing Center (which was quite apparent at times last season when he looked outright awkward playing on the wing) and he's also made it well know that he wants to play on one of the top two lines.
I suppose it would depend on how this season plays out. If Staal is successful (and kept on the line assuming that Therrien doesn't pull his change-each-line-every-two-seconds tactic), Madden believes that there is a greater possibility that he will remain in Pittsburgh; however, there's always that slim chance that he could struggle on this line and where would that leave him (or the Pens)? I honestly don't believe that Staal will fail at Malkin's side -- that line is just pure magic and creates endless opportunities when they're on the ice, but the closing of Madden's article sums it up best:
Staal’s fate isn’t up to Therrien, or Malkin, or anyone else. It’s in his own hands. Staal will start the campaign on a line with one of hockey’s top offensive juggernauts, and he’ll be standing right in front of the net while the NHL’s most talented power play weaves its magic. If he can’t produce, it’s on him.
Either way, Staal will get paid. But if he can establish himself as a full-time left wing and put up solid numbers, he’ll likely get paid in Pittsburgh and be a contributing part of a burgeoning dynasty. If that’s what Staal wants, it’s his to earn.