We show that attacks that are commonly believed to be hard, such as isolating 50% of the mining power, are actually within the reach of anyone with access to a BGP-enabled network and hijacking less than 900 prefixes.
Of course a lot of people have access to the required equipment and have the required knowledge to try something like this. If it was easy to do, someone would have done it at least once already. However, the paper is rather interesting as it describes a lot different scenarios and proposes some solutions. I haven't found any relevant information beforehand, but to address this point:
7.2 Longer-term measures
Encrypt Bitcoin Communication
BIP 151 is supposed to encrypt the peer-to-peer traffic to make individual analysis harder.
I'll see if I can get some direct feedback for that paper.