There is very little hope.

Here is the latest revision (November 2014) of the recent paper this topic (May 2014) which explains how anyone can link seemingly anonymous bitcoin accounts to IP addresses.

These recent de-anonymization techniques can be easily implemented, and are also expected to distinguish between different users are sharing the same IP address and hidden behind NAT.

Bitcoin and TOR

In addition the authors describe a technique to make bitcoin clients ban IP addresses which correspond to TOR exit nodes, so that no one in the bitcoin network will be able to increase their anonymity by using TOR. In general two of the authors have published another dedicated paper  (October 2014) in which they claim that using Bitcoin over TOR is actually a bad idea.