Let's be clear here.

Anonymity can be maintained even if the pattern of communication is not "normal". What you need for anonymity is for the parts of the system(s) you interact with to not identify you. This certainly should apply to the nodes you interact with directly, so they should be under your control (e.g. the user-agent software, the computer you use, the facility the computer is located in, etc.) Further out, the system components have to not have a centralized ID of the endpoints. Cellphone networks DO have a centralized hub, namely the cellphone company. The key to anonymity is to make sure that none of the parts of the system can identify you, either because they don't require a centralized ID, or because the ID provider / facility / computer you used to access the system is unwilling or unable to identify you.

The way that governments and other organizations combat anonymity is by requiring various systems to identify other parts of the system (e.g. cellphones) with unique identifiers before letting them use that system. There are only two ways to defeat this:

1) Create a fake user-agent, to impersonate existing identifier(s), or

2) Circumvent the requirement to identify oneself.

The first one will put individuals you impersonate at risk, but it is likely they'll be let go and not subjected to "rubberhose cryptanalysis". The second one will eventually attract the attention of the governments. If they can set things up in such a way that systems (e.g. Lavabit) that refuse to identify individuals are somehow punished, their license to operate revoked, etc. then this should prove a deterrent to anonymity.

In the real world there are plenty of systems in the world who do not care about who is sending the data through the wires (net neutrality is related). Some of them are tunneled over other systems. Tor is an example, Freenet is another. They use primarily legitimate, identified accounts (e.g. someone in their home using an ISP) to transmit this tunneled information, sometimes over a protocol that is indistinguishable from TLS. As long as things like SSL and TLS are allowed, this will be possible.

As long as such a system is distributed enough that it doesn't have a central way to shut it down, it will be infeasible for governments to intimidate enough operators of the system into shutting it down. These are the ways to have true anonymity. PerfectDark and Freenet are used in countries with oppressive governments.

Note that you can have a consistent identity and still be anonymous! This can be great for reputations, e.g. of app developers, app stores, antivirus companies and reviewers of software. I have written a lot more on the subject here:

http://magarshak.com/blog/?p=114

What the article describes is that steganography is hard. Acting in the real world while avoiding suspicion of a government with access to many systems (telephone systems, etc.) is hard. Which is probably a good thing. Terrorism is a problem of technology. 300 years ago it was nearly impossible for a few guys to kill thousands -- they'd be apprehended and stopped first. Today, there is more and more technology that empowers individuals to kill may people. This goes back to the machine-gun debate, but basically as capabilities grow (3d printers printing guns, for instance) so does the surveillance. Sadly the surveillance isn't going away, because the technology for both is only increasing.