I don't think you can underestimate the McDavid factor. There has to be some cross marketing deals the Oilers take advantage of. Oilers fans travel well. Right up there with Leaf and Rangers fans. They also have some history. History seems to be important to valuation. All 6 of the original 6 teams are in the top 10 in valuation. Building generations of fans helps over time among other things. It's interesting to see how low the 2 time Stanly cup winner Panthers are. Even though they are a great team they either don't have the flashy player to make the highlight recaps or the team history to support the demand for the product.
As far as over all team valuations go you would think there would be a point where they would top out but I am not so sure. I recently read a book titled Rock and Roll is here to pay. It was published around 1975-76 and went over the economics of the music industry from early in the century to that time period. What was thought of as a lot of money then seems so quaint right now. A rock and roll band might get 20 grand to play a show at the Aud back then. The point that struck me though was how human economics were evolving. No longer needing every cent for food, clothing, shelter, and transportation the US population slowly began to have money to spend on records, stereos and concerts. The obvious parallel is to sporting events. Tickets that coast 100's to thousands of dollars are now the norm to a portion of the population. The economic cycles will stunt the growth I would think, but the demand is there.