Google's Pixel Launcher seems due for a complete rework, as indicated by a brand new version found on Pixel devices at one of Google I/O's many Sandboxes. The Sandboxes are places to demo certain features, and while this one was for Instant Apps, with those largely unavailable at this point, the new face of the Pixel Launcher stole the show. The first thing most people are going to notice with this new version of Pixel Launcher is the absence of the solid white "Google Pill" in the top left. It's been replaced by a translucent gray bar sitting between the app dock and the navigation bar. A tap on this allows you to begin searching by typing. The link to Instant Apps comes in when searching from the top of the app drawer; while you can only search for apps that are on your device in the current Pixel Launcher, this one allows you to search the Play Store, presumably giving you the ability to find and launch Instant Apps right from that screen.
The focus on a more cloud-centric experience is quite clear in the design of this new launcher. The search bar has been moved to a more natural navigational position, between the app icons and navigation bar that see extensive use, and gets more screen real estate. The prominent search bar inside the app drawer is the real star of the show. Presumably, once Instant Apps are ready to roll on a wide scale, this will be where most users will spend the bulk of their time, rather than downloading every app that they need. Instant App compatibility is ready to go in the Android Studio 3.0 preview that launched today, so it likely won't be long before Instant Apps, enabled by modern LTE and 5G networks, become an integral part of the Android experience.
The person recording the videos below asked about the new launcher, but the Googlers on hand weren't giving very straight answers. When asked if it would appear in Android O or on the new Pixel, the representative showing off the launcher backpedaled a bit before finally settling on just saying that it isn't available in the current preview version of Android O. Since Android O will presumably drop alongside or close to a new Pixel device or Pixel family, the app could end up debuting on the new hardware. Likewise, it could just as easily show up in a dev preview of Android O leading up to that point. In any case, nobody has been bold and sneaky enough to grab the APK and leak it from its California home as of this writing, so don't expect to run this on your device any time soon.