Corus - I don't disagree that having the MBA is good for the rest of your career. . .the knowledge is still there. Sure, you learned it, you own it, and the fact that you took the initiative to do it will always mean something.
But, there really is a shelf life for certain things learned in an MBA program. Some things learned, such as GAAP (accounting practices) and other fundamental-type courses will always be valid, or at least for many years. Here are some examples of things I'm talking about that expire:
MIS (managing information systems) courses: Computer technology changes rapidly. I'm sure courses 10 years ago were different than courses today. A big topic in my MIS class was the strategy of outsourcing IT. Was that a valid strategy 10 years ago? Will it be a valid strategy 10 years from now?
HR management: It doesn't get much more b.s. than this for engineers, but employment laws change. Plus, professionals' expectations change. Flex time, job sharing, and on-site daycare may have been reality for only forward-thinking companies 10 years ago, but a whole lot more companies implement these things today.
Global management: China wasn't much of a market force 10 years ago. Emerging markets are always changing. Political climates also change and affect global business practices.
Plus, I think employers who are paying for MBAs sometimes want employees who know all the right buzz words. I definitely disagree with implementing ops-management-strategy-de-jour, but there are still hiring managers who will expect you to know what the latest management guru has written some book about, and every 25 year old hot shot MBA will be able to recite it forwards and backwards.
I guess the future applicability of the MBA really hinges one how you are trying to leverage the degree. If it's just a checkbox on your job app to prove you're a management quality person, then it's probably good for a long time. But, if you were hoping to use that course in Global Strategic Management to position yourself for a management job with your favorite conglomerate's Bangkok office, you better make that job switch as soon as possible.