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.
Well not to a Gmail account (since you can't change your Google account email address), but your Google account and associated purchases is not deleted: https://support.google.com/a/answer/1257646
Just set up your MX with some other service if you are not happy with Gmail, or start running your own SMTP server.
I think the parent company misunderstood the process as being required to move to a new Google account. That's not the case as far as I can tell from the support document. The account remains the same, just have to pay for the service.
"How does the upgrade affect my current G Suite legacy free edition subscription?
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.)