Re: tablets, as they are now, are a dead end
@Grave,
Semantics aside, I think you're right on most things there, but tablets already can be, and are, used in many of those ways.
I'm surprised not to have seen more 'out of the box' integration with traditional PCs, such as using a tablet as a second monitor (and dragging files onto its desktop to transfer them... though this might confuse the metaphor), but a fellow commentard says it can be done fairly easily.
When I used to wrote reports, I was a bugger for printing out drafts and sitting in a comfy chair with a red pen... a tablet with a suitable screen could replace that. For someone who just writes, a tablet has plenty of horsepower- they just need to work on the ergonomics- fixed with a keyboard and case/stand combo, arguably better than a traditional laptop because of the separation of screen and keyboard.
For content? My mate already has a home server that transcodes and streams Blu-ray rips on the fly to his (or anybody else's, with permissions obviously) phone, tablet or laptop.
For serious work? Yeah, you can already use tablets to remotely access your home machine (no doubt the process can be polished). For real heavy-lifting, why buy the fancy CPUs yourself for intermittent use, when you can rent it by the cycle? (suits some tasks better than others)
Watching movies in the bath? Happened years ago in a very user-friendly way: My mate's new PSP automatically introduced itself to his PS3, which in turn introduced the handheld device to his NAS.