But I still use my old gmail for one thing: Point of contact for the my domain registrar. Do you have any suggestions for how I can solve this?
A second hosted email domain has an additional benefit - it allows you to also control your recovery (secondary) email, such as you'd add to your banking/financial website, etc. and not have any of your email options where they can be taken away like this post. It's trivial to have one of the email hosted providers do an IMAP pull from your GMail account, so you can still keep it around just manage it as an external account (such as for your Android login needs).
With it, I have email from multiple domains doing what I want. I also have a <username>@fastmail.fm which has only been provided to one person: my domain registrar.
If you pay someone to handle your email this is a good approach, IMO.