Think of King Kosmos as a future version of Per Degaton, much as Immortus is a future version of Kang.

Well, with Maggin's Lifetime Ban from the DC offices, we'll never really know how far he would have taken it, will we?
If the King Kosmos = Kang thing is so obvious that everybody picks up on it instantly, and are sighing when they read this post saying, "Did you pick up that comic like, YESTERDAY?" Then I'll shut up.
But it's surprising what you assume everybody knows that they don't. I thought everybody picked up on the fact that the main character of STAR WARS was named Luke, when the creator and writer was named "LUCAS" - what, at least to me, was a Marty Sue self-insertion. But apparently when I mentioned it people were surprised.
Interesting however, that on an interview on this site from 1971 or so, Maggin and Bates were irked by Marvel's approach and yet adopt it themselves - for instance, giving Luthor a strong characterization as a sympathetic misanthrope and misfit instead of a truly wicked and antisocial personality, and further, how Maggin worked to incorporate the Guardians of the Universe into the Super-Legend, AND, to top it off, created a character obviously inspired by Kang...Maggin may say one thing, but really, isn't imitation the sincerest form of flattery?