Is there any reason why Microsoft is keeping the languages separate or
will they eventual replace all the languages with one, just to
simplify?
In all probability, both VB.Net and C# are here to stay ("stay" in
computer terms, anyway), both have large user bases. J# and c++/managed
are only a little less secure, though if java ever tanks, J# will be
dropped in a second IMO.
But I'd expect a whole lot of the other language implementations to go
away, especially the small ones that MS did for the original framework
largely so that marketing could boast of .NET's multi-language
capabilities.
And why do people keep talking about switching to C#.Net, is there
something special planned for it?
That depends on who you hear talking. In most US markets, C#
programmers make more money on average than VB.Net programmers, so
there's always some talk on those grounds. And it seems that every time
that Whidbey news comes out, there's some grumbling about VB.Net
programmers being treated as second-class programmers, but I don't
anticipate many people switching because of it.