I'm more worried that PM is still fairly new and in beta. These hobby businesses come and go, and changing one's email is a huge pain. What's saying that PM will be around for 10+ more years, like Gmail has?
This is mostly because changing your email address is a huge pain. Once you're using your own domain, changing email providers is like changing web hosts or domain registrars: Some work but not a big deal.
Or, as an easier solution, a dedicated email forwarding service. I've been using one for about 15 years now and changed the actual email service provider a couple of times just by updating the forwarding address.
Of course then the problem is to identify a reliable email forwarding service that won't go anywhere.
