I also own the Galaxy TabPRO 8.4. As far as I know, there aren't any updates forthcoming. As for this device getting the latest version of Android, it would be nice, but I wouldn't be holding my breath for it. We are, after all, talking about a device which is now over 2 years old. Sometimes Samsung will send out the occasional minor update to fix bugs but beyond that, I doubt that we'll see anything major.
That being said, you can check out the following Sammobile website link where you can get news on the latest firmware updates available for your Samsung device.
Firmwares - SamMobile