The more interesting trend, as you mention, is what this is doing to the career opportunities of the next generation. Since boomers aren't retiring, the top jobs in many organizations aren't opening up. And so many people my age and slightly older (I'm a very early Millenial) believe there's no possibility for advancement on the corporate ladder. Hence the recent trend towards entrepreneurship among young Gen-Xers and Millenials.
Whether this results in a net inflow or outflow in the capital markets depends on the real economic growth of all these startups. If they really do open new markets, then the economy expands, more money flows into savings, and the stock market keeps going up. If they don't, then the non-retirement of boomers just means a transfer of savings rates from the young to the old. Boomers won't have trouble supporting themselves in old age, but they'll have to support their kids.
He did teach me that entrepreneurship is a lifelong pursuit.
I'm thinking there's actually a large pool of cash sitting on the sidelines, from people that didn't drink the Kool-Aid during the 04-07 boomlet. And once there's a signal that this has bottomed out - maybe it'll be Dow 10K, or S&P 1K, or the bankruptcy of the last of the big-5 investment banks - all that cash is going to come flooding back into the market, and they'll be a big pop in stock prices. I'm waiting a bit - I think there's still more bad news that hasn't been factored into the market. But it may be time to start buying soon.
If you do not believe you can time the market though, then being 100% cash is as bad strategy now as at any other time.
But certainly demographics have failed to predict the future in the past, and personally, I'm amazed at what's happened to my income in the past 5 years or so (I'm in my 40s and saving like mad - though all in cash right now).