>a future where true general purpose computing starts to disappear

I think just the opposite happened. All we had were general purpose computers, then we added "easy to use" computers in the form of smartphones and tablets. It just allowed a lot more people to take advantage of computers, it did not remove access to general purpose computers for the rest of us. Personally, I love the idea of a bifurcated world where the less technically savvy use devices that are far more restricted and secure. I really like that my parents can get a device, like an iPad, that does everything they need from a computer (email, facebook, light web browsing) without having to worry about malware.

Not at all. If anything, the more companies like Microsoft and Apple push for locked down systems, the more open source SBCs and hobbyist computers we'll see. There will always be a market for open computers, and the past few years have seen an explosion in that market.