This would break a cool indieweb "hack" with DKIM - webfistbump, which lets folks participate in webfinger even if their email provider doesn't support webfinger, like gmail:

https://www.onebigfluke.com/2013/06/bootstrapping-webfinger-...

(I suppose you could just re-opt into webfistbump every time your email provider is about to publish their DKIM key)