I think the inevitable threat to telcos is going to happen. That threat is the most obvious over the top, under the floor, or through the pipe marriage of services, media, signalling and features. It's when Microsoft decides to marry Skype and Lync together, oh, and toss in Messenger, and if you want, Exchange too.
Let's look at the facts. Hundreds of millions of people have accounts with at least one of those services. Businesses use Exchange and Lync. Consumers use Skype and Messenger. Don't forget that Skype owns GroupMe, the SMS and Group SMS service too.
Put them all together, with one giant switchboard, enable termination in and out the way Skype does today, add in some SIP trunking for the Enterprise that doesn't jump fully to SIP but uses Lync and everyone is reachable.
What do they need to do..well, unlike phone numbers, country codes, area codes and numbering plans, all you need here is an ID (noted that Skype and Messenger have them) and an email address. Just about everyone online has one except those who don't pay the bill and can exist only with IM and Skype.
From there the MSFT Switchboard takes over, figures out how to get the call to where you are, and voila, your connected, all without the telco which become the pipe, not the phone service.
Sure there's going to be a lot of heavy lifting in the middle to make this work, but the writing is on the wall, and the telcos have got to see it...