Those who are bemoaning the graying (or greying if you're English) of the hobby and the lack of interest of individuals in their 20s to 40s are making some questionable assumptions. Not necessarily wrong, just questionable. The average age of active model railroaders has been north of 50 or even 60 years of age for many decades according to many sources who should know. Thus we won't know how many of today's 20-40 year olds will be interested in the hobby for sure until 10-30 years from now . I didn't get real interested in the hobby again until I was in my 40s, and I was relatively privileged financially and space-wise.
Another issue we fail to appreciate is that people are living much longer and in better health. Psychologically and in terms of life expectancy, the model railroaders of the 1940s and 1950s who were in their 40s-50s (seemingly young to us) could only expect another 10-20 years of good health and life. They were born before vaccinations against childhood diseases existed, before antibiotics were available and before we understood the role of air and water pollution in cardiovascular disease, stroke and cancer. So they correspond to today's 60-70 year olds in many ways. The hobby has always been, as many have pointed out, a hobby of middle aged men and older. Middle age has moved. 40 is no longer old-- medically, psychologically or in terms of life expectancy and health expectancy. Someone now 70 has on average 15-20 years of likely life expectancy (on average). In yesterday's NY Times obituaries on-line the three deaths were of individuals in their 90s. Every Sunday, our newspaper has several people in their 100s and many people in their 90s. In the 1970s I knew of one patient who died in their nineties in 8 years of medical school and residency. Life has changed.
So predictions about what current 10, 20, 30 and 40 year old individuals will be doing hobby-wise when they are in their 50s, 60s and 70s are not terribly reliable. Not to mention that in the 1940s and 1950s, the population of the USA was perhaps half what it is now, so 0.5% of the population being interested in model trains today is the same number of people as 1.0 % in 1946 or so. People are living much longer and in better health, and with more disposable income in many cases now than 30 years, much less 50-70 years ago.