The population of 60 and older persons in the US is holding it's own - much better than in decades past. So this will be reflected in the congregation. Your observations about the lack of younger members is spot on. Just scan those in attendance at assemblies - the 20 somethings are virtually non existent. I think that younger people born in the "truth" - in the last 30 years - really pick and choose what they believe. Information is easily available and shared via the web. Unlike my generation, they are not isolated or uninformed.
The WT's recent push through the website - kids videos, activities, worksheets - attempts to halt the exiting of young adults. The GB wants to indoctrinate (and create an emotional attachment to the org) very young ones as soon as possible.
Anthony Morris admits that during the introductory part of the Be Jah's Friend video.