I think a potential problem is the way everyone has concentrated on the OS, which just isn't a big selling point for the mainstream user.
How many people actually go into a phone shop and say "Show me something that runs Symbian/Windows Mobile/OS X etc"?
Phones are sold to the vast majority of consumers based on the brand of the device, not the OS running on it. People buy Nokias, Samsungs etc.
It's only really PDA users and tech enthusiasts who worry about their phone's OS, but they're a tiny fraction of the phone world as a whole. Android needs to be in handsets that are desirable for other reasons.
The developing world particularly is in need of vastly more capable handsets, at very low prices
Actually Symbian could do very well in that market, for example the 5500 Sport (which runs S60 3rd Edition) is currently on sale SIM-free at about 120 euros plus taxes, and I suspect we'll be seeing S60 devices under the 100 euro barrier next year.
Particularly when you think that much of the developing world will never have laptops or other PCs, and have already been using mobiles as their "personal computers" for some time now.
Yes, this is a very important point which seems to be lost on rich world journalists. A smartphone with TV Out is becoming an increasingly plausible replacement for a PC, and possibly the only computing option for most of the world's population.
Televisions are far more ubiquitous than monitors, and phones are far more ubiquitous than computers: if a TV and phone can act as a computer, most people will just use that combination because most people simply don't have access to a dedicated PC.
USB host mode may be another important development in making smartphones cheap alternatives to PCs, because USB accessories such as keyboards are incredibly cheap and well within the budgets of virtually anyone who can afford a basic mobile phone.
If a smartphone could output to any SCART set at, say, VGA resolution and use a mouse and keyboard, that is going to be just about good enough for the majority of computing tasks that most people would want to carry out.