Now that I've seen a few, it seems to me that in most cases those who are bidding for they're own brand are going to see their ad spend climb ever so gently...
Bad example search for "priceline" -
Ad Sitelinks look cleaner, right in your face, and so more tempting than the organic sitelinks.
Good example search for "kayak" -
they're not bidding on their own brand so you don't see Ad sitelinks (at least for exact match "kayak") letting organic results do their job, for free.