I think people are looking to closely at the first degree attack -- a trusted partner is pwned. If this is the case, there's far more interesting things an attacker could do. It's not too hard to envision a scenario where an attacker does not have access to embeded assets, but does have access to logs.

1. You include a script such a TypeKit. The typekit deliverable itself is not owned, but bad actors have access to typekit.com logs.

2. You use a smaller third party add on service that itself uses a logging service such as PaperTrail. PaperTrail is hacked, providing attackers access to logs.

3. You reference no external assets, but your site contains external links in the footer. Users click the navigation links rather than completing the form. You have leaked the token to whatever site that is. You are at the mercy of their log storage. YES, this does actually happen. User's click crazy things.

As I mention in the article and in other comments here: this is not likely to be exploited. Fixes, however, are not too difficult. Even adding the not-quiet-fully-supported `meta` tag to your head is a good start.

If I read this article today, I'd think, "That's interesting. let me make a note to check that out." It's not a hair-on-fire security situation, but it's not "not a problem at all" either.