Actually it doesn't sound like you'll be able to see even the first open.
"E-mail marketers will no longer be able to get any information from images—they will see a single request from Google, which will then be used to send the image out to all Gmail users."
The problem is that it will be Google requesting the image. So you'll see the headers for the request, but they will just tell you that someone with Gmail opened your email, nothing more. And if the cached version is sent to ALL gmail users, you won't see any subsequent opens at all.
Open stats have always been inaccurate and marketers know to take them with a grain of salt, because they rely on the image download and many users don't download images. So all this really means is that the numbers are now known to be even more inaccurate than they were known to be before.