How do I change my Apple ID while keeping my iCloud?

The relentless (daily) instructions from Apple to unlock my Apple ID, despite having 2FA turned on, are driving me nuts. I suspect it's because I was an early adopter and the email address I use for it has been circulating for nearly 25 years, and automated systems just try to force guess the password. Let's say it's bob@mac.com.

Evidently loads of people are having this problem cos I see the same complaints on this forum; the answer generally given – including by Apple – is to change your Apple ID to something more private and unguessable.

The procedure they advise is: go to your Apple ID settings, DELETE the existing bob@mac.com address, which will prompt you to select a new Apple ID address.

That's all very well, but Apple ID and iCloud have historically been rather bound up together, and it makes me nervous. I've been on the verge of doing this for a few days, but always bottle out, cos I strongly suspect that deleting the bob@mac.com address as an Apple ID on my Apple devices (phone, Mac, whatever) might well lose me access to my iCloud login with the same address (obviously the same password, etc) which would be an absolute disaster (email, calendar, all manner of other stuff.)

I can't risk trying it unless it's a copper-bottomed certainty that this won't happen. I don't suppose anyone is in a position to tell me that it's fine... but if anyone can tell me, it would be most welcome.

[Re-Titled by Moderator]