I'm always skeptical of non-sports media diving in and offering their perspective, like the Wall Street Journal's sports articles in their weekend section that are often laughable. But in this case, it's Forbes and it's money and valuations and they've been doing it for some time now so there is some legitimate basis behind the numbers (though Forbes has run into issues/claims of inaccuracies in other sports with their valuations).
As far as the Pens go, they are valued at $155 million, which is 22nd in the NHL and higher than the Islanders, Thrashers, Capitals and Blues among others. The Islanders need a new arena even more than the Pens do. What is interesting is that the Thrashers and Caps play in new buildings but remain very low in valuations. Lack of support from a small fan base is the reason. So when the Pens get their new arena in a couple of years, despite the fact that they will remain in a "small market", their valuation should skyrocket up the list, with the primary reason being the strong and rabid fan base they have cultivated - they recently were ranked as having the third strongest in market brand strength in the NHL by Turnkey Sports and Entertainment. Only Buffalo and Detroit were higher and the Pens came in at #20 overall in all four major sports (and you'll want to check out who is #1 overall).
With a new arena and continued strong fan support the Pens could easily move into the top half of the league in revenue - they could rank with the Lightning, Wild or Senators (though with the Sens only if the dollar strengthens, but that's a whole other conversation).