The key in the message was used in my last announcement, so that establishes continuity there. 

But regardless, all mails I send are signed automatically by Gmail using either the gmail.com consumer key (for my posts to this list) or the google.com corporate key (for my posts to the bitcoinj lists), see dkim.org for more details on this. Whilst this is not signing in the GPG web of trust sense, realistically the Gmail DKIM keys are much safer than any key I could create/maintain, and my ability to sign mail as hearn@google.com is controlled by hardware second factors and various other rather intense security systems I can't discuss.

I've considered just not having the additional Bitcoin-key based signatures at all, but it would help keep continuity in the case that I leave Google or if there's a DKIM key rotation.