The third and likely last Chrome 68 build has arrived in the Chrome OS Dev Channel. The new build is 68.0.3440.4 (Platform version: 10718.4.0) and is available for most devices. If you have a device in what is considered the alpha channel for the platform, you should have the update available to you. This build follows the update from last week to the channel.
With the promotion of Chrome 67 to the stable happening this week and next, it means that 68 should be promoted to the Chrome OS Beta Channel, likely next week. Remember that Chrome 67 is expected to be released for Chrome OS on June 5th.
As for Chrome 68, there still is a bit of mystery around what will make the final release but there are a lot of code changes that have happened under the hood. Usually when things start making their way into the Beta channel, we have a better picture of what has made the alpha phase cut and can be tested more broadly.
Right now, Chrome 68 is expected to be release on or around July 31st for Chrome OS so there is still a lot of testing to do. It is likely, based on timelines, that there will be 4-5 beta builds released before it actually makes it out to the Stable Channel.