Google has begun converting display ads into AMP format, so that ads on AMP pages will load faster than traditional ad formats into those pages.  With the AMP conversions, ads will load within AMP pages on average of 5 seconds faster.

For site owners utilizing AMP, this means that ads on AMP pages will load much quicker, so your site visitors will see ads instead of the AMP ad placeholder that is displayed on AMP pages initially while the ads load:

For site owners that are struggling with monetizing AMP pages, this could translate into an increased in ad revenue, since more visitors will be seeing ads instead of that placeholder, especially for ads higher in the page.

From an advertiser perspective, those advertisers will also be able to get their ads before potential customers on those AMP pages, as the ads should load well before scrolling on the page.  When ads were slower to load, visitors to the site the ad is displayed on might not get the opportunity to see and engage with the ad.