I'm also interested in this and made decent progress on a git-style content addressed image where everything is identified by hash and residency determines what

I'm also interested in this and made decent progress on a git-style content addressed image where everything is identified by hash and residency determines what's in memory. For example, there's a filesystem on the image that works this way and you can page over the "cold" non-resident bytes for very large files that you would not want to hold in memory. You don't persist the state of the full image continuously to the host disk, but any given state (new programs, new runtime state, filesystem) can be saved via a delta, not a full rewrite, due to this representation. So this is a little different than what you are talking about, but I'd say it's possible.