I’m in favor of this change, BTW. This is likely going to be recommended soon as well for forums by Google. sameAs links and interactionStatistics in particular, but more information to assist in clustering like given there can be useful as well.
And that’s a good general structure recommendation (ProfilePage → mainEntity → Person). I wish there was an account type in schema.org but that’s been slow to find traction so we’re working with what we have.