I did this (there was a lot going on in life) and they just added the balance to my 0% interest loan.

I was able to talk to an Apple rep and get a kit sent out and get the credit re-added. This was in 2024.

Pretty easy.

I'd expect a charge to my credit card, or a bill. If I didn't pay the bill, I'd expect another bill and a late fee. Eventually, I'd expect the debt to be transferred to a collection agency which would harass me about it for years and report my nonpayment to credit bureaus. If it was a large enough debt and I ignored all of that for long enough, I might expect to get sued.

I would not expect to get locked out of my cloud storage, app store, email, etc....

Indeed, that and missing a pretty serious sounding email from Apple.

I 100% commiserate with the author and have missed important stuff before, but yeah, this article reminds me of the importance of making a habit to read the emails from my "important" accounts each morning. I setup some guardrails to help save myself from my own humanity, e.g. monthly "pay CC" calendar events.