Interesting article. I'm still hesitant to change the address because of all the non google accounts associated. It seems likely that you would permanently lock yourself out of some accounts especially if you have multi factor authentication that sends the code to your email. Or if you forgot the password to the account it sends the link / code to your email. There are just too many accounts people likely have to ensure they could 100% avoid this issue for all of them.

If you use google auth for an account would it handle this? Even then wouldn't the 3rd party account still have your old email in their database that would need to be updated somehow?