That was a totally different case. Yami Marik and Marik are two different characters. Here it's still the same Kalin, only reborn as a Dark Signer. So the "Dark Signer" part is not necessary to begin with, unless they plan to include normal Kalin as well.
That wouldn't happen. Kalin and Dark Signer Kalin are the same character. As a Dark Signer he's just possessed by the power of the Earthbound Gods/Immortals. Yami Marik, Yami Yugi, and Yami Bakura are completely different characters from Marik, Yugi, and Bakura. For Marik, he's a split personality. For Yugi and Bakura, they're the spirits of Atem and Zorc respectively
I don't have hopes fot that happening, while i would love thousands of times more to have the Reaper Kalin instead of the Dark Signer, Duel Links it's about their iconic character no the developed one, same thing with Zane which we stuck at Hell Kaiser and not the good but cool one