Forgive me for asking a subjective question but I'd really like to know where is the .NET development headed in the near future? Are we going to see more ASP.NET developers or will there be more demand for Silverlight/WPF && WinForms developers?
This is such a broad question. I think it is safe to say as long as .NET is around, there will be no shortage of ASP.NET development. I think Silverlight will be prevalent in a particular set of niche development but ASP.NET MVC will be where the majority of .NET Web development will be at, unless there is a large, steadfast group of WebForms users. As for WinForms vs WPF; I think its safe to say Microsoft would like WPF to be the future of the client and it probably will be but the uptake will take awhile. These are just my $0.02.
The .net platform is en 80% of the pc market and silverlight is improving VERY very fast. All the app are going to the cloud and silverlight 4 is very good for porting your app to the cloud. By using the same very familiar visual studio you can deploy your apps to the web using all the tools you have for desktop or asp.net apps. Silverlight is going to be an important player in the next years. Look at the web office app in skydrive.
All three?
They all cover different markets that (to a large degree) simply do not overlap. ASP.NET (and in particular, ASP.NET MVC) is great for "classic" web development and is the way to go if you like the stuff coming in HTML5, Javascript and so on. Silverlight is for when you're doing RIA or writing Flash-killer apps. WinForms is for desktop development and is great for rapid development of line-of-business software. WPF is great on the desktop for consumer software (where eye-candy is just as important as functionality). WPF can also be used for line-of-business apps, but I personally find WinForms to be a little easier to grasp (even if it's not as powerful in terms of data binding and so on).
To be honest, I think the question is kind-of loaded. If you're trying to decide which "area" to get into in order to find a job (or whatever) then I would suggest you follow your heart, not the flavour-of-the-month. Do what you find most interesting, and - if you're good at it - the work will come regardless of which area you chose.