I honestly could see Crosby playing for the Penguins for all of his career. I mean, I don't see the Pens not making an effort to keep him on the team and pay him well, as he is the foundation and captain of the team. I believe Crosby when he says he doesn't see himself playing anywhere else NOW, but sometimes people change their minds. Look at Dany Heatley. Also, you can say a trade involving a certain player is unlikely, but never impossible. As they say, if Gretzky could be traded...
I'm not as sure about Malkin though. Him buying a house doesn't really convince me of anything. I don't think he wanted to stay at a hotel or teammate's house until 2014. He can get a new house (and bring his parents with him, haha) to a another city if he leaves Pittsburgh.
Bonus Answer: For the sake of answering this at all, hmm... Brooks Orpik? I guess he's still young. So long as they pay him, he might stay.
Penguins fan. Pittsburgh native & resident.