You may not have heard much from it lately, but PlanetSide 2 still is a thing for PlayStation 4 and it's taking signups for an closed beta right now. Head here to register.
There's no word when the beta will begin for the PlayStation 4, just a notice that your info was submitted and is appreciated. Planetside 2 was intended to launch on PS4 earlier this year. The beta likely will begin sometime next year.
Note that the signup is only for a chance to get into the closed beta; nobody's guaranteeing that registering gets you in. Planetside 2 is one of a couple dozen free-to-play games Sony is looking to showcase on PS4 in the coming year.