Weakest Link in a Large Scale Attack on BTC Commerce?

I would really like to hear many expert opinions on this in general, but I also have one idea of my own. The idea I have for a large scale attack could start after collecting data from ISPs or specific targets like Blockchain.info by gathering which IP addresses visit specific wallet balance pages or transactions pages.

For example I think it's highly likely that the first IP address to view a wallet balance after a transaction is the owner of that wallet, especially if that page was found by querying the full address completely, as opposed to clicking through the recent transaction feeds which any bystander may do. I am making an assumption that enough individuals using BTC visit Blockchain.info or the few major blockchain websites.

The next assumption is that some entity with all that data could then use it to harass, hack, or press 'legal' charges on the individuals. So, is this a possible threat? Or are there more effective attack strategies?