> sure, kids will type their homework reports completely on their phone.
Most homework is not a report. How many of those did you write in your ~12 years of primary education? I suspect you could count them on your fingers.
Most other homework will be (is already) web apps, with very little typing.
> now, the computer of the future may be a handheld device that plugs into a full size screen and keyboard, but when used in that mode it's a desktop
You may perhaps call it a desktop at that point, but it isn't a "legacy office PC", and this mode will be the non standard way to use a device (it is already for me).
> (and the apps are seriously lacking for current mobile OSs)
As for apps? I thought the whole reason for apps is because your phone was too small to display a full web page (oops, did I say that out loud? I hope the app producers didn't hear me!), or for games. Really, why do I need apps on a tablet, so I can pay $5K for a picture of a diamond? The most common apps will all be (are) free open source utilities that come with the devices.