Yeah I figured that would be the case. Owning your own keys is fine and all but if widespread adoption is attained then there will always be breaches. With software doing the signing too you can't really keep it air gapped.

I wonder if a pimary/secondary key system could work, like you create a primary key on hardware then sign to associate a secondary key with a single identity. That way if the secondary key were compromised you sign a new one and unlink the old one.