A TL;DR for the article below, feel free to jump to the section you want to read more about.
What ~will~ might be announced at the event:
As a side-note, I want to say that although this article is meant to be comprehensive, a lot of the content will be short and straight to the point. This is because of a couple reasons, the first is that I didn't get a degree in professional writing, much like many bloggers around me. The second is that if I took my time to completely flush out this article, it would be posted after the event, at which time I would be writing another article with all the actual news that gets announced. With that out of the way lets get into the content.
This is the baseline phone, if you are familiar with the past Nexus phones this is basically the Nexus 5 but with a great build quality. The price is rumored to start at \$649 for the 32GB baseline variant. It comes with a 1080p (1920x1080) 5 inch display, Qualcomm Snapdragon 821, 3 or 4 GB of ram, 12MP rear and 8MP front-facing cameras, 2,770mAh battery. It also will come with USB-C, a fingerprint sensor and the regular 3.5mm headphone jack.
Both the Pixel and the Pixel XL have been leaked in photos as shown below:
A lot of the initial feedback from leaked photos of the Pixel and Pixel XL was negative because of the size of the top and bottom bezels. I have since come to accept the bezels, I think they will be bearable, what I will miss is the smaller screen size compared to my Nexus 6.
The Pixel XL is basically an exact copy of the Pixel, except for a larger screen size coming in at 5.5 inches and at a higher screen resolution of 2560x1440.
This is the interesting one, first off I am still sure that Google will release a new 4k Chromcast, some are calling this the Chromecast Ultra, however I feel like Google has been shifting away from the Chromecast name towards just Cast. So we might see a change in the name of the chromecast device. Other than 4k support not that much as been leaked about this, they might not even spend that much time on it during the event.
The price is expected to be \$69 dollars, so double that of the baseline Chromecast, and the current generation of Chromecast's will still also be available.
We have known for a while that there have been some devices running Android 7.1 in the wild, most likely some Googlers with the new Pixel phones, or updated OS's on their own devices. This time Android might be splitting up into two separate versions, or at least two variants, the stock Android and then the Google version of Android. This has been the trend ever since the release of the Google Launcher with Google Now. Now though Google is starting to bake more features into their variant of the OS through Google Play Services.
I am really looking forward to this mainly because I believe Google can build some really great features on Android. There are many people who use Android without using any Google services, and they are the people who will probably be for Google doing this because this is going to be a seperation of Google and Android.
This is the new and amazing news that only broke this week. Google Andromeda is a merger of Chrome OS and Android and is supposedly going to be on the Pixel 3 laptop in Q3/4 of 2017, and maybe even the new Nexus 7 tablet announced at this event. There really isn't that much that is known about this OS yet, I kind of doubt that the Nexus 7 will be released with it at this event because there has been no information about the OS yet.
Some rumors have been pointing to Huawei-made Nexus 7 that will run Andromeda, however if this is actually true I doubt it will be unveiled at the event because nothing else has leaked about it.
A lot of the hype around this has been caused because of a marketing stunt by Google Cardboard in the UK recently, however that stunt was only for Google Cardboard. We don't know that much about the Daydream Viewer, other than some patents that Google filled recently.
This is one of the exciting products to be released at the event, Google Home is going to be a competitor to Amazon's Alexa and going to be Google's greatest attempt at expanding into the home since the chromecast launch, or even the Nexus Q.
This is sort of a wildcard one, we have heard some about this device (or devices) but it seems odd to launch this when Google Home, and Google OnHub both exist. Supposedly this is going to be a competitor of Eero, a mesh wifi network system.
Ultimately I am mostly excited for the Pixels and the Daydream Viewer, I expect to buy a Pixel xl, and a Daydream Viewer. If I had a TV I would also consider the Chromecast Ultra, but I won't be going for the Google Home device simply because my apartment is small enough that I can use my phone or tablet at all times with 'Ok Google' voice commands.