Today Google made an announcement on their blog in which they expressed a desire to "more closely align" their efforts on the consumer side of Gmail with G Suite's Gmail. It might sound humdrum, but it's a biggie. That's because Google wants to bring the two more closely together by taking a page from G Suite and no longer using the content of your emails as input for personalized advertising. This is expected to occur later this year.
This is a pretty big change, but some outlets seem to be reporting that Google is cutting personalized ads from Gmail entirely. That isn't the case, and the blog post makes no such claim. All Google has stated is that "consumer Gmail content will not be used or scanned for any ads personalization," not that personalized advertising is going away. They have plenty of other sources of information for that, like the text of your searches. Tons of people even answer long and detailed quizzes about themselves, many of which are used for targeted advertising, all for mere cents.
Even so, as an avid user of Gmail since 2004, I hope that they have enough data from other sources to continue making the same level of profit off each advertisement. I'd hate to see any unfortunate changes or cuts to the service in the future to compensate for losses. Given that 1.2 billion people use the service, according to Google, I imagine they wouldn't take any unnecessary risks with it.
This change doesn't mean that Google won't be serving up targeted ads, but it does mean they won't be reading your email to do it. At least, someday.