Particularly since Ghav and LadyLorraines points about functionality seem the biggest remaining issues. The first hurdle was taking the internet through the general publics "what?-nerdy-trendy-useful-vital" progression, and the original connection speed issues hung around for most of that, but for most needs of most people the speed seems good enough now (finding and maintaining a connection is usually the greater concern, from what I've seen). Once security is generally perceived as adequate the biggest issue with utility will be the interface itself. Touchscreens and wireless connections are great, since you can't put a keyboard, monitor and router in your pocket, but all the content and power in the world won't interest anyone who can't access it. That's what the whole issue is about, right, bringing the sheer masse of online data to consumers on the move?

In terms of availability I don't think we're far from the point of saturation, but if miniaturization and functionality could be easily combined laptops would've replaced desktops (and desktops would've replaced mainframes) long ago. You can only expect so much flexibility from something you can fit in a pocket and operate with one finger. If nothing else, a pocket sized display requires more switching from window to window because you can't view as much data at once. Maybe I'm getting old, or maybe it's just because I don't have any of the cool cutting edge smartphones (those are different "maybe"s, really), but until that obstacle is overcome I don't expect major fundamental changes, just cosmetic improvements and streamlining (and a lot of the highly touted "improvements" are more about marketing than performance). Reading PDFs is one thing, but a portable device capable of using Word, Excel and PowerPoint won't appeal to most people if it's still using a desk/laptop is still much easier. Virtual storage may get around a smartphones inability to use a terabyte hard drive, but interface issues are more challenging.

It's an interesting coincidence that you posed this question right as I'm deciding how to write a thread about the Sprawl Trilogy on the BMB.