We have successfully moved to the new Google Apps Marketplace using Omniauth2 etc. Yesterday our app got approved by Google. In our listing on the Marketplace the new Chrome Webstore Item Id is in place. But when I want to make any changes to the listing it says: "Vendor is not one of the owners of the current listing". The app still has the old Consumer Key, Application ID etc. From the documentation inserting the Chrome Web store ID should be sufficient. So basically we still have to app versions with two Applications running.
What else is needed to migrate completely to the new version?
If you proceeded with the migration of your app from Marketplace V1.0 to Marketplace V2.0, the application in the old market place will be listed until the Marketplace is completely deprecated. It is no longer possible to edit the listing on the old Marketplace, only editing the new listing under the Chrome Developers Console (https://chrome.google.com/webstore/developer/dashboard).
Keep in mind that the new Marketplace will run independently from the old Marketplace. The new one runs under the Chrome Web Store, and the ids for each store are completely independent. You cant link the old app to the new id.