Yes, those who are working for companies that still require IE6 (and there are some!) are screaming "no!" right about now. Past reports have indicated a lot of YouTube viewing happens at work.
Reports show evidence that YouTube is going to start phasing out IE6 support. A message to a TC user who went to YouTube shows the text:
"We will be phasing out support for your browser soon. Please upgrade to one of these more modern browsers."
Heheh. Now why would Google do that?
What about the millions of Windows Mobile 6.x phones that will have flash support soon but no support for the IE6 browser they'll have as their default. Some phone vendors will probably install Opera or Skyfire to get around that.