For many people there is a natural progression, often based on where you live:
Example, many people on the East Coast or Midwest start skiing at smaller more-local areas. If you live in the Detroit area maybe you started at one of the local areas and progressed to resorts in Northern Michigan. Some like in NYC maybe started skiing in Vermont. Later, these people progress into skiing western resorts. Maybe even further down the road they start during trips to Europe, Cat skiing, or heli trips up in Canada. Sometimes these people may never go back to the smaller places. In other cases, people return back to their small local hill even after doing trips to bigger resorts.
I know several people in the Detroit area who refuse to ski in Northern Michigan. They simply fly out to Colorado or Utah for 1-2 trips/year and that is all they do. I have friends who live on Long Island and gave-up on skiing on the East Coast. They simply fly out to Colorado or Jackson and do about 4-5 long weekend trips per winter.
Myself on the other hand, ski in Northern Michigan about every other weekend, travel out west for one week-long trip + 2 long weekends, and occasionally ski a few nights at the small local Detroit areas when the conditions are decent.
Looking back at the history of skiing, there are a few events that have let to changes and closures of smaller ski areas:
1960s: Jet-Era: Thehuge growth in air travel, along with the development of larger western resorts led to a significant number of smaller ski areas in the Midwest & Northeast to close. People more easily go fly out to larger resorts instead of driving trips to smaller areas.
1970s: Snowmaking; larger ski areas that could afford snowmaking systems put them at a huge advantage over smaller areas.
1980s: Weather: A few bad winters in various portions of the US, put many smaller ski areas out of busiess. These didn't have snowmaking, and often ran on very low margins between proft and loss.
1990s: High-speed lifts: Many smaller areas found themselves disadvantaged against larger areas that were spending huge amounts of money to upgrade their lift systems. The cost of new lifts is now expotentially higher than what it was in previous decades. However, the 1990s were actually a relatively more stable period, primarily since the economic growth was so high during this era
2000s: Economy & Insurance/Overhead Costs: 2 major economic downturns had a direct impact on the amount of skiers - the post 9/11 downturn, and the massive fall-off in 2008-2009. This led to noticable declines in skier visits at many areas in many regions. Real estate took a huge hit in many areas too. During this time the cost of doing business rose significant and ski area insurance costs sky-rocked, and energy costs increased too.
2010s: Changing demographics??? - I think this is a major risk looming on the horizon for many smaller areas. The core group of skiers are getting older and some dropping out of the sport all-together (especially with older women 65+). I don't see the growth on the younger end of die-hard skiers and boarders developing to replace this group. It's not really an issue directly for more major resorts as they will always have the demand, but is a real issue for smaller areas. I don't see the younger generations snapping up vacation home real estate like the boomers either. Ski areas to a decent job of getting kids into the sport but how well are they able to retain them once they go off to college or grow-up?