Absurdly wrong, marketers already use a unique image URL for each email recipient, and Google has no way to know that all of those point to the same image. So they won't see "a single request from Google", they'll see one request from Google per successful delivery to an inbox.
Now, an open question is if Google will make that request when the email is actually opened, which would allow marketers to determine if and when the email was read by the user, or if Google will make the request as soon as the email is received. The latter would enhance users' privacy at the cost of bandwidth for Google, but early tests indicate that they don't actually do that, waiting for the user to click the email to make the request.
I'd like to add that there's no possibility the Gmail team is stupid enough to not have considered this. They must know full well what they're doing, and marketing this as a privacy enhancement when it's actually detrimental to privacy is willfully dishonest.