Easyreader: Your points are valid to some extent, but I don't see the WTS going away any time soon. As sir82 pointed out, there's a large chunk of the population that wants to be told what to do. Groups like the WTS fill that role.
Your first point (youth retention) has been a problem for a long time. For at least 20 years, I've heard elders and CO's state that only 20-30% of young ones stay in (I recall the Pew study from 2008 puts it at 37%). Nonetheless, the increase over the last 20 years has been HUGE. The fact of the matter is that the WTS doesn't need its young people--at least in the short and mid-term.
There are plenty of suckers...I mean sheep-like-people...out there who are desperate and ignorant enough to join. And that will be the case for the foreseeable future--especially when China opens up, likely some time in the next decade. I predict that we'll see 10 million JWs within the next few years.
Your second point (fewer males able to teach) is a more recent phenomenon--at least in the U.S. I think it is a factor in the WT's recent downsizing (no more book study, etc.). The WTS has several options on how to handle this. I don't think they'll get to the point of having female MS/elders, but they may have women handle more non-teaching roles, such as literature, microphones, sound system, territory, accounts, etc. This way, the elders and MS could simply handle teaching parts and public talks. Also, the WTS could continue to downsize. One easy thing to do is get rid of that farce of a "congregation Bible study" in the mid-week meeting.
I agree with your third point (science is a problem for the WTS). But the WTS seems to be attacking it head-on. There were two brochures released at the conventions this year on evolution/creation. Also a few years back (I think it was 2005 or 2006), there was a "special" issue of the Awake aimed directly at creation/evolution. The WTS is borrowing heavily from the "intelligent design" movement.
Also, the WTS has backed away from some of its embarrassing positions--particularly that the "creative days" were 7000 years each. Today, you can be a JW and believe in the "big bang" and that dinosaurs lived millions of years ago (which wasn't the case when I was growing up as a JW). I don't see the WTS taking this much further, though.
But remember that something like 50% of Americans don't accept evolution at all. So, the WTS/JW faith is not really out of the mainstream on this issue--at least in the USA. It's probably a different story in Europe, though.