I've been thinking about "The Future" (capital T, capital F) lately, and wanted to consolidate my thoughts a bit:
1) There are no facts about the future. My friend Jeff Wacker, a futurist for EDS, pointed that out to me once and it really stuck in my head.
2) Long-term strategic planning is kind of silly, on several levels. First, there is very little accountability, because the people making the plans generally won't be around to see them come to fruition and won't be exposed to the consequences of being wrong. Second, there is precious little opportunity to learn from experience, particularly for long-range planning, because we don't directly experiences the results of our decisions and predictions - and if we do, it's too late.
3) We tend to overestimate what technology can do in 10 years... and underestimate what it can do in 50 years. I read that somewhere - don't recall the source.
4) When we talk about the future, we are really talking about the past. When we talk about the distant future, we're really talking about the very recent past. (That is, we are extrapolating trends, and the more recent the trend, the further into the future we think it will extend.)
4.5) Futurists don't really believe in change. That is, they think the future will be a certain way IF trends A, B & C continue and the environment/market/threat/etc responds the way it has in the past. These predictions basically rest on the assumption that things will continue, unchanged. This is not necessarily a bad assumption.
5) 20 years is a long time. It might make sense to spend 20 years on a research project, discovering some new knowledge, but a 20 year development project to build a new thing (particularly a large one) tends to deliver some components with obsolete technology while simultaneously relying on / hoping for some new technological breakthrough for other components, which may or may not happen (see #3 above). Never mind that the need/market/mission/threat has probably changed significantly over the 20 year development time (see #1 above). Perhaps that's why the DoD and the GAO both say we shouldn't spend more than 5 years developing something (the key word being "should").