I think the reason it's going to be harder is because of the Facebook and Twitter advertising. At first I thought the more the merrier, but now I have a different take. If it gets competitive, it means that advertisers need a better price and return. That wouldn't lead to better money of better paying clicks as publishers. Being at the bottom of the food chain isn't ideal obviously. So to me, it's the influx of other options for advertisers which will likely lead to more challenges regarding Adsense earnings. Traffic wise? Can't see that getting even more difficult in 2014. Google having to entice advertisers? That is something I could see especially if Twitter and Facebook make some headway.