Utter nonsense. This is 2012 not the late 60's.
Kipketer, Rudisha, Kaki and many other top 800 guys from the past 20 years have been/are trained by European and African coaches who will be fully aware of the use/benefits of weights for middle distance runners. Makhloufi and Kaki are trained by the same guy. Why would he encourage one to do weights and not the other? If it was simply down to incorporating weights into their training then all 800 guys would be doing it. It has been shown in the past that some guys benefit from it and some have not. The whole point of a coach is finding the best training types and methods that work for that individual athlete.
You make it sound like an African has never seen a gym before! Do you really think Rudisha's coach hasn't at least looked into incorporating weights into his training, especially given his appreciation of Coe and apparently being a knowledgeable historian of the event? For all we know he already does use some kind of weights in his regime.
Your vision of all these naturally gifted and ignorant African athletes running free around the natural terrain where they live, without a clue as to how talented they are, is both fantasy and extremely patronizing to all african athletes.
Throughout the EPO era only one man broke 1:42. The event, one of the most contested of all t&f events, has hardly moved on at all since 1981, despite advances in tracks, training, etc. To suggest that a whole "plethora of mid/high 1:42 guys will go" to 1:41.0 in the next few years is ludicrous.
If it happens it will only be through the introduction of another undetectable PED as mentioned elsewhere on this thread, and certainly not down to Africans picking up weights!