Yes, and Hacker News calling it "killing for existing customers" is ridiculous. No service or access is being "killed" here - they are simply asking to start paying for it like everyone else.
Your current G Suite legacy free subscriptions and related services will continue to function as they do today, until you self-upgrade or we upgrade you automatically to one of the new editions."
That "until" is really ambiguous - does that mean services terminate when you self-upgrade?
If you cancel it, your account is converted to an ordinary external domain Google account AFAICT. You need to migrate your email out of Google/Gmail to get service messages over email, but you can continue using your Google account as an ordinary Gmail-like account - only difference being that you handle your email yourself (because you didn't want to pay Google to do it for you.)
Just set up your MX with some other service if you are not happy with Gmail, or start running your own SMTP server.