They don't need to break it, Skype already offers backdoor access for governments.
I vaguely remember reading something about the skype team saying they would "cooperate" with law enforcement officials, but I'm not sure if that meant actually listening in on encrypted conversations or just sharing the IPs and time of connections to servers.
This reads as FUD they made up to sell ad views.
If somebody who is reverse engineering Skype found it, and it would eventually be found, the company would be ruined.
Even if skype came out and said they were recording every conversation, I don't know if all that many people would stop using it. There wasn't all that much outrage over immunity for the big telcos, for instance.
Or did you mean the company would be ruined for some other reason besides loss of reputation? Maybe I misunderstood the comment.
It's more intentionally malicious to distribute software with a backdoor than to do what AT&T did so I really think it would upset people more.
Remember the Sony 'rootkit' fiasco? And that wasn't even really harmful, just annoying.