As shocking as it’s sound, AdMob will not run via DFP. This change was coming as Publishers were running Admob & Adexchange together inside newly introduced Yield Group leading to multiple requests to Google’s Demand. This change was announced way back in october last year which led to new yield group with admob as yield partners not saving.
As bigger publishers had Ad Exchange, Admob was never the choice for big publishers. However, the smaller one’s relied on it heavily for app monetization without including any additional SDK. They could just simply run AdMob via a Yield Group. While new group creation was deprecation on October 2018, a complete removal of AdMob as yield partner will come into effect by end of January 2019. You can know more about it here.