While I think that businesses are going to skip Windows 8, I don't think that Metro will be going away. I would even say that the desktop will be gone completely in Windows 9 and that businesses will love it.
It took me some time to find a use for Dropbox - and yes there are plenty, but I had already similar services setup on my own, with remote access etc. So even after I started using it, I never felt that it is safe for real professional stuff. And here are the reasons why that is and how Google Drive resolves this issues.
Why is Pinterest so addictive for so many people? Because it's the first social sharing platform (it's not a full social network) that allows you to follow just specific "boards" of a user. That's a first...
I'm curious to see if there will be the same outcry on google+ with the new design as you always hear on Facebook - but I like it.
Facebook for example has become big enough to swallow all upcoming and already established competitors. After acquiring Posterous, now Instagram.
Seth Godin has written a long and thoughtful peace about the current and future evolution of the internet, mobile computing and the internet of things. It's an important read also for designers, who see their challenges in the problem they are solving right now, or the client they are working for (at least it looks like it).