Is a 1/2.3" sensor good enough for tv?
Small sensor means two things: increased depth of field (everything is in focus, no soft backgrounds) and more noise in low-light conditions. If either of these are a deal-breaker then consider changing. Here's why maybe you shouldn't:

To get a large sensor camera with the ease of use and ergonomics of this camera you'll be looking at cameras like the Sony FS7 which with lenses is going to be around the $8k mark, maybe close to $10K all up.

Otherwise if you do go down the DSLR route you'll find that simply getting a GH4 probably won't be enough for broadcast work. You'll also need a good on-camera monitor because the built in monitors are way too low res to be able to judge focus critically, probably an external sound recorder, maybe also an external video recorder if you want to record raw or proRes, maybe a follow focus handle, maybe a matte box, and—since you'll have all these extra bits to carry—a rig to put it all on. At this point it will weigh about as much as a family sized refrigerator and look like something from Mad Max. I know, because I've lived it.

You won't have motor zoom, and unless you get a cinema lens (eyewateringly expensive) you'll have to put up with stills lenses: no manual iris control on the lens, focus measurements are very approximate and usually go something like 1ft, 2 ft, infinity, and there's no parfocal zooming—meaning that focus changes as you zoom.

The shorter depth of field also means that you have to really stay on top of your focus. When I first started shooting with DSLRs (5DII) I was going gung-ho with wide open lenses, and discovering that when I looked at the footage in the edit suite that if the subject moved at all they'd go completely soft. It wasn't until I got an external monitor that I could reliably get useable footage from the thing. For documentary shooting, although you can get beautiful results when conditions are right, it really isn't the right camera for run-'n-gun.

If beautiful bokeh is worth it to you, then go DSLR, but if getting the shot is more important then go with something with good ergonomics, that is first and foremost built as a video camera.