There's been a huge trend lately where people are moving away from traditional computers (especially in businesses). There's a large shift in the industry where people are bringing their own devices to work (largely iOS devices) and hooking them up to corporate networks. The phenomena is known as consumerization of IT and it's catching on quick. It's to the point where Microsoft is actually a bit threatened by this, as some businesses are considering throwing out the "traditional" PC all together. Granted, this isn't across all companies in all industries, but it certainly is an alarming trend.
The biggest worry for IT organizations today is the ability to secure and manage these devices. Right now, there aren't really any great solutions and the ones that are out there require a lot of implementation and administration. While this is less of an issue for the regular worker, how do you deal with your CEO's iPad if it gets lost? Do you have the ability to wipe the device remotely? How do you keep all that confidential information from falling into the wrong hands?
I agree with you, I don't see the keyboard and mouse going away any time soon for most applications. That's why Windows still works with a keyboard and mouse. There are certain parts that work better today than in the past (most notably the search functionality) that put much more emphasis to people using the keyboard. If you haven't already, I'd challenge you to switch over to Win8 in a production environment and use it every day for all the tasks you do now. You'd be surprised at how little the metro interface gets in your way.
I was never a huge user of the traditional start menu. Once Vista came around and I could just search for what I was trying to run, I almost never used the "all programs" section. I would just hit the windows key, start typing the name of the program, and hit enter to start it. Windows 8 hasn't changed that functionality, but also gives me a few new toys to play with and use (improved multi-monitor support, for example). Metro is there if I want it and need it, but I can easily ignore it if I don't.
I'm typing right now on a laptop running Win8 in desktop mode (no touch screen) on IE10. If I showed this to someone, they'd be hard pressed to tell it wasn't Win7, save for the missing start button.
We're at a point with touch technology where it's not an expensive add-on anymore. I'd venture to guess that a lot of the mid-range laptops coming out this fall will have touch screen capability. I'm looking forward to one in particular (the Lenovo Yoga) which will be in the $1k price range with ultra-book specs. A lot of all-in-one consumer PCs that are sold today already have touch screen monitors and they don't really have a huge premium over the non-touch counterparts. Sure, your $300 netbooks will still be non-touch, but I can see that changing as well.