One theory that I have that I think is cool and would be amazing is that the night angel books and the lightbringer share a command time line and universe something like where the night angel books came first then the lightbringer ones. Like Kyler could have been the original light bringer or even the one guy from the library where kip is doing the card thing. I am just one that likes to see if something can connect and if it can see how. So feel free to either agree with me on this point or prove me how these to series can never be in the same universe.
The Ka'Kari were color based so the theory isn't too far out there. The only hiccup is white because white in the Night Angel series was seductive and the white in Lightbringer is pure. But, that wouldn't be the hardest thing to overcome for a writer of Week's caliber.
So, maybe Kyler destroys the Black Ka'Kari and in the process the intelligence that is in it goes mad, thus making black luxin a source of powerful madness in the world. Because all the other Ka'Kari were based on it, their magic explodes on the world transforming the basis of how magic is used and perceived. It's a bit of a stretch, but not too much.
Maybe there could be a 9 Kings card for Kyler that Kip absorbed. That would be a fun chapter to read.
White wasn't just seductive, it was used to create illusions. Essentially Khali used it to become seductive and seem like a goddess to common men. Remember she was actually meant to be quite unattractive and used it to fool people in to thinking she was attractive (or something along those lines). Using light to create an alternate image of yourself could be described as drafting, so not to difficult.
I think the more difficult one is the Silver Ka'kari which make you impervious to blades. Otherwise, yes in principle something could be done to marry the two.