Mepps said a few days ago that water is the next power and that's all they have to announce so far. We'll probably have to wait until water is out and working just fine for an official announcement.
Due to memory allocation and memory saving. The PS3 has limited RAM, thus powers can be very limited in both animations and reusing icons is convenient for developers and design. Example( electric shockwave is the same animation as celestial's smite) Water is supposedly the last power to be added until the company can either drop PS3 or find another way to increase memory space( via new UI, increased server capability, etc) As far as white and black lantern being possible for powers. It was made very clearly that the community doesnt want any more lantern powers, especially since blue lantern was turned down.
IMO we only need 1 more lantern power and that is for Healers. Then no matter what role you enjoy running you can have a ring.
I don't know what power can I choose, I like the Lanterns, but not their skills. And it would be great if when we choose Light powers we can select the color we want.
It would be cool to grab a ring and mix it up with your own color choice but sadly the 7 rings are all color coordinated, so not much change there. A healer one would be AMAZING hopefully it happens because I love the way the ring looks but sadly HL is weak and needs a revamp and from what I hear rage is more for the tanking than the DPS side of things, hopefully we get indigo. It makes the most sense since you restore fallen teammates and switch them to the good side once again as seen in the duo corrupted Zam. Wouldn't mind having something different, I have spent 30$ on power tokens trying new powers already