Since you are new on this forum, I will be nice
Correct, there is no update for this week.
There will be a new update for Mi Mix 2 once the various dev-teams have completed the Android 8 testing that they deem necessary for a "Beta release", i.e. without "critical failure bugs".
This release will come when the work is done, it could be in the next week or two, but there is no guarantee of any date, so you (like myself and many others) have to wait patiently for the dev's to complete their work.
The first release for Android 8 will probably entail some extra effort, rather than a simple OTA update (perhaps similar to the Android 6 to 7 update for Mi5, explained in the first post), but I DO NOT KNOW FOR CERTAIN, JUST A SUPPOSITION ON MY BEHALF.