32-bit to 64-bit - Obsolesence Pains Again?

robotsrule asks: "Having been in the computer industry a while I distinctly remember the pain of making the 16-bit to 32-bit transition, when Windows made the change to 32-bit support. Any developer who remember the joys of thunking and other kludges that were meant to help code conversions also remembers the arcane marathon debug sessions too. I have not been keeping up with the latest Microsoft Longhorn technical news, or the plans that the Linux community has for 64-bit platform support. Does anyone out there have a reliable prediction for the amount of system shock we are facing when either Longhorn or 64-bit Linux comes out? Will I lose all my favorite 32-bit development tools again as I watch the backward compatibility support dry up as the 64-bit O/S platforms are adopted? Or are the O/S manufacturers making happy noises about long-term support for existing development languages and tools?"