They would. But this would be easy. I have a friend of mine who works for F5, which is similar to Cisco. They sell the networking hardware that does routing of very high speed traffic. They love to pack extra “features” into that hardware to win customers over their competitors, and charge more.

That networking hardware enables reading/modifying traffic in real time. It also includes forking a copy of traffic, even as it travels at very high speed.

This attack would be trivial. With a CA’s private key, they can make their own MitM cert and return that, which they can do at scale since they can hand out the same cert to all users. It would be more work for them to handle TLS encrypt/decrypt on the router during the MitM attack, but straight forward and they wouldn’t need to add latency of routing traffic towards NSA because the routers could handle all of the MitM encrypt/decrypt/fork work.

Even Iran pulled this off with TLS to gmail.com for their citizens. http://news.cnet.com/8301-27080_3-20099421-245/google-users-in-iran-targeted-in-ssl-spoof/

Fortunately, this is not a problem.

HTTPS without trust would be like switching from postcards to letters, which still can be opened and read by the postman, but require active effort of opening and re-sealing the letter. This would make mass surveillance a nightmare, as NSA would have to actively man-in-the-middle every connection ever made to spy on everybody as they are now.