The Penguins also have had a close to Norris caliber defenseman during Crosby's entire tenure, which the Leafs currently don't have.
True, but I'm talking about what people were thinking a few years ago (not back in 2009 before Crosby and Malkin even signed these huge deals). Letang is fantastic, but he was missing time due to illness and injuries. This past cup, Letang didn't contribute at all to this recent Stanley cup run so the Pens didn't have a Norris caliber defenseman for the vast majority of this season and all of the playoffs.
The 2009 Penguins won because Crosby and Malkin had near historic playoff runs. It obviously wasn't sustainable, seeing how they didn't accomplish anything from 2010-2015. That kinda proves the other guy's point, because the Penguins lack of success during those year was due to the things you mentioned and then some.
They didn't win again until their depth was phenomenal (which the Leafs already have satisfied), their defense was deep and fit their style of play and they had an elite goalie. The Leafs don't have those last 2 yet.
See, that's where I disagree it proves the other guys point for exactly some of the reasons you stated. First off, the Leafs depth is phenomenal and they have a very good prospect pool as well. Once they sign their young players to their next contract, I don't see that depth just going away. Also, their defense, on paper, isn't any worse at the core of it than the Pens was this past season (- Letang), and IMO, will only get better. They've got a fantastic front office and a great coach. Of course, Crosby is the best player in the world and Malkin, when healthy and motivated isn't far off. Still, the Leafs talent upfront is one of the best in the NHL from top to bottom IMO.
Goaltending, you are right in that Murray was elite, but a couple years ago, when I felt people thought that way about the Pens, nobody expected Murray to suddenly come onto the scene and be what he is. I also think Andersen can be better than he was this past season, his first on a new team with a new system.
Of course I'm not saying they 100% will win a cup in the next 10 years, but if I had to pick 5 teams to win a cup in that timeframe, they'd be one of them, acknowledging that it's very tough to win one so odds are against pretty much any team, and that a lot can happen over this timeframe.