The nature of banner advertisements on a mobile device lends itself to accidental taps which takes the user away to the advertisers landing page and out of your app. Google's mobile ad network Admob has added an extra step to help thwart that by putting confirmation prompt when a tap to an ad occurs.
While this might sound bad for a developer wanting to get paid on clicks, it could end up increasing user activity in your app if your ads are placed in a location on screen that has a lot of accidental taps, and increasing your CPM because taps to ads will be more intentional likely to convert.
Developers could see a dip in revenue as the change rolls out, but if it goes well prices to ads will increase because advertisers can be better assured their promotions won't be accidentally clicked on by someone not interested in their product, and as ad prices increase so does your payout.