Can Kayn have character inking?

He can, but it would look like this http://i.imgur.com/ZyT9KRa.jpg

From RiotTokkelossie on the Kayn Reddit AMA:

The current implementation of inking is performance intensive for what it does so we're exploring the possibility of phasing inking out in favor of a better solution. We wanted to ship Kayn without inking to get player feedback and get a sense of how noticeable it's absence was. The reason we chose Kayn to test this is that the Assassin form's hair uses transparency, which is something that inking interferes with (which is another downside of the tech)

So basically, they are looking into other solutions that play nicer with features like transparency and are better for performance. Kayn was just a good test candidate to have inking disabled because it doesn't look good with his hair, and he happened to come out at a similar time to when they were exploring new ways to go about outlining characters.

One of the solutions that they're looking into is shown here.

pls just put the inking back, its annoying as f*ck playing kayn without it . it really hurts my vision