This is referring directly to the robots.txt file, which many people use to control these functions. The reality is, you will still be able to leverage and utilize many different functions if you don't want Google to index your content.

The two most common will be:

(1) Noindex in robots meta tags (also can be found within the All in One and Yoast Functions. This directive is supported both in the HTTP response headers and in HTML. It will remove the URL form index when crawling.

Search Console Remove URL tool. You will be able to remove content from Google's search results directly from your Google Search Console account.

So this will actually be a moot issue, it will lead to some work for those with comprehensive and sophisticated robots.txt files that are used for managing these, but in terms of most websites that are handling through the robots noindex meta tags or anyone using Google Search Console, it will be a non issue.

Kyle gives a great answer

Thank you for bringing this up. Now we have a clear picture of what to expect.

Laura