So what, gpg keys are unlimited resource. Just generate new ones whenever required. I've been using that strategy. Just like you don't want to reuse your password everywhere. If you don't want to be anonymous anymore, you can sign nonce with your official and with your temporary key. Some seem to claim that OpenPGP doesn't support ephemeral keys, but it does. You just need to generate new keys and use those, when ever you want/need to.