I agree with Sahil on this and I think the time has come where developers (let's focus on that group for now, as otherwise the scope will be even bigger) have to make a choice in which sub field they'll be comfortable: be it office development, UI development on asp.net, UI development on windows, service oriented software, architecture as a whole, database oriented code etc. etc.
This has already begon some time ago though, ASP.NET alone is too huge to become a deep expert in that and know everything else in .NET as well. If I look at myself, I also feel I'm seriously behind: what I've done with .NET 3.0 technologies is just a bit of WCF, but that's it. When I look at it, much more than reading up the details, write tests to see if everything works and if not add some code to make it work is all that's possible without losing knowledge/time over investigating other areas of the .NET framework.
However, I also have to say: it's not a misery as well: for example even without deep ASP.NET knowledge it's still possible to get a page up and running. Perhaps you'll spend more time on details as an expert but it's not impossible.
Though things like office, sharepoint and other related stuff (except WF)... it's great MS releases all this code but frankly I don't care: not from a business point of view (our code doesn't affect these technologies) nor from a CS point of view: nothing really new is provided.
WF is different as it's part of .NET as well, so we've to make sure our code works with WF.
And looking back, does anyone remember commercial server for example? MS has released a lot of stuff during the years, which was used by some, but not by all. As long as they use the framework as it is entitled to be used and the .NET framework isn't polluted with gazillion classes which are actually very specific, it's not a showstopper. Sure, droves of developers won't know every area of the .NET framework, but that's already the case now. Heck, even I don't know every detail of LLBLGen Pro anymore, I sometimes have to look things up as well