The SoCal locals and Mammoth do have somewhat of a countercyclical relationship. This was first evident in my formative ski season of 1978-79, which remains the best ever SoCal season in my experience. I heard at the time that the good local snow resulted in a 10% decline in Mammoth's ticket sales, to which Dave McCoy reportedly responded, "That's OK, most of the new skiers from a year like that will become Mammoth converts during normal years."
The next significant event was the early 1990's SoCal recession, which coincided with changing demographics. The new young, price-sensitive generation was about 75% snowboarders, and when Snow Summit/Mt. High cut ticket prices and built big terrain parks, they maintained or increased business while Mammoth's skier visits declined by nearly 1/3 from the 1982 and 1986 peaks. Mammoth/Intrawest responded by 2000 with even better parks and the cut-rate Mammoth Value Pass.
The recent economic crisis was probably a mild parallel to the early 1990's situation. Though 1992 and 1993 were excellent SoCal seasons, while the past 2 have been only average. Nonetheless Mammoth responded this April by reopening the MVP to new entrants after closing it 4 years ago during the boom years.
Back to Baldy/Waterman: The 1990's demographic change was at least as bad a hit to those areas IMHO as to Mammoth. With minimal snowmaking they will never compete with Big Bear/Mt. High in park construction, and most SoCal snowboarders coming from surfing or skateboarding do not have the skills to handle the steeps and variable ungroomed snow of Baldy/Waterman. So the potential daytrip clientele for Baldy/Waterman is far smaller than 25 years ago. The numbers back this up. During our last big season in 2004-05 Waterman was closed but Baldy was open from Oct. 28 - May 22 and sold 50K tickets vs. 500K at Mt. High and probably 750K at Big Bear.
In this situation I see Mt. Waterman at a severe competitive disadvantage vs. Mt. Baldy. Baldy has 4x the lift-accessible acreage, a modest altitude advantage, and is a shorter drive to 90% of Southern California. For the new snow days Waterman's road is more likely to be closed, and even if it's open I'll be at Baldy nearly every time. I'm a skiing "nutcase," so I can figure out a few situations where Waterman will be better (like last Feb. 14), but overall I rate to ski Baldy 4 or 5 days for every one at Waterman. With SoCal's erratic snowfall that works out to about one day at Waterman every 2 seasons.
They both seem to be in the same boat as New England's beloved Magic Mountain VT: Interesting hills, bad outlook.
I see the analogy there, but in a different way. There's a limited demand for that type of ski area, so perhaps only the best one per region is viable. In Vrmont Mad River Glen has some advantage in terrain and a big advantage in snow over Magic most of the time, so that clientele is more likely to stick with MRG. In SoCal Baldy's advantage in terrain and accessibility will likely prove as decisive. In each region I would like to see both areas prosper, but I wouldn't place any bets on it.