Marketers have answered that question with their wallets: Facebook ads do work, especially when they're slotted in users' news feeds, on desktop and mobile devices alike. In the last quarter of 2013, the company's ad revenue increased 76%. Ultimately, though, the big unknown that could imperil Facebook's future is how well it will age. Will people continue experiencing the compulsion of wanting to check it several times in their day? Facebook is no MySpace. There's no implosion coming; it has its hooks into us too deeply. It's home to years of photos that the less prescient among us didn't think to back up elsewhere and a network of connections that can't be furnished by any competitor. Get the full story at AdvertisingAge