IPv4->IPv6 is a known problem, that will take a lot of work and money to fix, but should be all but invisible to the end user.
Y2K was a known significant problem, that took a lot of time and money to fix, but the end result was almost invisible to the end user, except for the media hype.
*grins* I know, my dad's been working for Microsoft since '94. I get regailed with stories about Y2K.