Let me clarify my point. Clearly we are *at* an inflection point for Windows OS, API's, and development. Microsoft chose to create this inflection point rather than a more graduated approach.
I am not predicting which way the market will go. I am definitely not that smart. If I had to make a call, the best I could say is that there will be some middle way, that a Longhorn victory will be hard fought path that extends well beyond 2007. But who knows? An accurate prediction is not the point.
I do think Wes, et al. have missed some key aspects of Joel's message though, reducing the discussion to a binary one of who will win, the old or the new.
One of the key aspects of Longhorn is that, Joel suspects and I've wondered on my blog earlier, *why* everything is rolled into an all or nothing set of dependent technologies. Clearly many parts of Longhorn could be made more independent and portable to older Windows platforms (even Linux, but that's another topic altogether).
The interesting aspect of this issue is exactly that Microsoft has avoided inflection points of this magnitude so far, but with Longhorn they are *creating* their own inflection point. Let's just watch how they play this out; Longhorn is probably more interesting from a business sense than from a technical sense.