Re: Heinlein's relevance today
I think RAH's work will be more likely to endure for his philosophic view point rather than his appeal to adolescents. I tend to suggest his work to psychology, anthropology and ethnology students who respond very well to RAH's exploration of human relationships and how they are likely to evolve under the influence of science replacing superstition in society.
For example:
Social conditioning against breeding with 1st degree relatives is a result of the increased number of defective offspring this produces. The parallel result of the small number of superior offspring this also produces tends to be less visible in terms of the average persons ability to understand statistical outcomes or even perceive the universe around them. The 1 in 4 offspring who exhibit reinforcement of the superior traits of their genotype tend not to hang out (too busy off being successful) with their more defective relatives and therefore the prohibition is further reinforced by social perception of a family group which is known to inbreed.
The Howard foundation is Heinlein's response to this - he even comments on the higher incidence of "defectives" in the early stages of the breeding program. However as the gene pool becomes cleaner through the preservation of the superior phenotypes and elimination of defectives from the breeding group (not killed just not bred back into the genotype). He enables the reader to overcome the EXTREMELY well programmed "screwing your sister is a mortal sin" ethnocentricity of a majority of human societies.
Show this to a University student studying philosophy, genetics, sociology, psychiatry or any related subject and they become almost instantly hooked.
University students (bouncers) are the most common juvenile form of the Academic (Martians) - Academics then mature into Professors (old ones). Professors set the reading lists which University students are exposed too
. I tend not to give RAH to teenagers - they haven't learned to think yet, but early twenties when idealism and intellect combine seems to be the best time.