Account handles will not recyclable (for obvious security considerations). So this seems more akin to "permanently disabled" rather than "deleted"
Conversely, if you take the advice of some to set up a personal domain for your email, you are basically committing to a lifetime obligation. If you later change your mind and let that domain expire, any future owners of that domain will receive any email that was sent to your old addresses.
Same way I may buy a home & get mail. Tomorrow if I sell that home I need to do change my address with senders, and make sure to put forwarding (maybe keep the old domain for few weeks/ this year)
You can set up a forward to your new email, and keep the old address active and forwarding messages until you're satisfied you've updated (or canceled) all the uses of your old address.
Then maybe start bouncing messages for a period of time before you finally shut down your domain.