It's not the lack of manpower, but insufficient knowledge transfer.

Nice article on CLO Magazine on upcoming changes in workforce, I quote the first paragraph:

"According to Randstad USA’s just-released “2008 World of Work” survey,
U.S. businesses face a serious talent problem with the coming retirement of baby
boomers. Of course, this isn’t news to most chief learning officers. What they might not realize, though, is the challenge lies not with a
lack of manpower, but with insufficient knowledge transfer."

This means in my humble opinion the learning profession is called upon to make this transfer of expertise happen! The retiring generation has a lot of expertise in its head (knowledge), hands (skills) and heart (behavior), and somehow that has to be extracted, transformed into learning that works for the incoming generation and delivered to them asynchroneously.

The rest of the article is here: http://www.clomedia.com/executive-briefings/2008/June/2247/index.php