Microsoft is likely to develop many of their new applications in .NET and
managed code.
However, the kernel itself is not managed code, and the millions of lines of
Office code will take a while before they come out in entirely managed code.
Also, it doesn't make sense for key internal components, like the XML
parser, or the SQL evaluation engine, to be done in managed code, although
I'm sure some folks would disagree.
Then again, if Biztalk server can be done in .NET, then darn near anything
can, so there's no guarantee. Who knows what's going on in the product
teams of Microsoft!
Will every existing app be rewritten in .NET? No. Wouldn't make economic
sense.
Will .NET last forever as the last real innovation in languages on the
Microsoft platform?
no way.
That means, someday, something new will come along, and we will all be
talking about millions of lines of "legacy" .NET code...
(I've been doing this for 24 years. From experience: The train never
stops.)
--- Nick