I don't think they're dead - but changing communication trends have created new challenges. Calling someone on their cell phone is considered rude and people are increasingly ignoring their office phones. As for email, we are inundated with an ever increasing load in email - making cold emailing less and less effective.
But the deeper question is "Is Cold Prospecting Dead". To that, I give an emphatic 'no'. Seasoned sales professionals like to prattle on about how its relationships, referrals, and the art of the pitch/close... but only because they've forgotten how hard it is to get the machine running.
Aaron Ross' predictable revenue is a modified version of traditional prospecting. People have to become specialized, disciplined, and rely on tools to help you be more efficient.
But the underlying concept holds true: In absence of higher yielding lead sources, cold prospecting is superior to doing nothing.
If you believe that principal, then you do *everything* you can to grow sales that is *NOT* cold prospecting... but the key is to 'grow sales'. In absence of any more effective method/technique, get back on the phones and email and become a student of prospecting.
Maybe the better answer is "Cold Prospecting is Dead for those that don't learn how to do it in today's changing environment"
Pro Tip: Communicating through LinkedIn, Twitter, and other online channels is still cold prospecting. Setting up tools like Cadence to handle your prospecting emails is still cold emailing... just more evolved versions of them :)