This is a really open question. With nothing specific to roll with here's what I can offer -

Everything old is new again. The world of online marketing is constantly changing so everything is new. That said, the basic ideas and methodology of marketing is rooting in behavioral science and psychology and can be applied smartly to modern marketing.

As to whether there is room for innovation. Sure. There's always room for that. And competition. And evolution.

There's a ton of data out there based on customer information that can be pulled from APIs from the biggest social platforms like Twitter and Facebook.

When you have that data you can do so much with it. It really depends on if you're looking to build an app or a service. Or if you're looking into creating some new platform.