The Epic Pass really breathed new life into a ski industry that was struggling to find its footing after the 2008 meltdown. From the 90s into the early 2000s, at nearly every major resort, real estate was where they were making most of their money. The skiing was meant to drive real estate development. In the span of just a few months, all these resorts lost a massive source of revenue, and their main source of capital. It just crashed and burned, ceased to exist. If you're running a resort, how do you recover from such a shock?
When Vail introduced the Epic Pass, it marked a shift in focus away from real estate. You could instead sell a lot of cheap passes, get people on the mountain, and they might spend on other stuff like food and ski school. It worked. In fact, it worked so well that Vail was able to vastly expand their portfolio of resorts, adding even more value to their Epic Pass. A lot of the resorts they acquired were ones that previously followed the real estate model and got burned in 2008. Unable to do anything other than limp along, they sold to Vail.
The resorts that weren't sold to Vail attempted to band together in different ways to offer new pass products to compete with the Epic Pass. Still, none of these could really go head-to-head with Vail until the Ikon Pass was introduced. That started the current era of the "Pass Wars".
This did have unintended consequences. Since you had a much larger passholder base than before, with a lot more flexibility, the best days of the season tended to get overcrowded. You also can't really price every resort differently, and so you have some that are underpriced and get overwhelmed with skiers.
I don't believe this is entirely due to the passes though, at least in the west. The entire region has seen a lot of population growth in recent years. I'd be willing to bet that this has more of an effect on resort crowding than fly-in guests who mostly book in advance. While they gravitate towards the holiday weeks, they are limited by the amount of lodging available at these resorts.
Oddly enough, the mega pass model has actually resulted in some resorts resuming investments in real estate, as they discovered they needed more lodging and housing in the area, so I guess it all goes full circle.
I don't see the mega passes going anywhere anytime soon. They won't be exactly the same, but they will always exist in some form. For them to go away would mean Vail or Alterra completely dissolving, and their resorts being sold off to independent operators. I don't see that happening.