Atlus has shown five new demon designs for SMTIV and some of them are linked to the Kamen Rider series, for example Yasushi Nirasawa worked as a creature designer for the Kamen Rider series and designed Asmodeus.
There are two other completely new demons revealed: Kouga Saburo, "a legendary hero from the Suwa domain", and Kyouma Aki the god of agriculture and knowledge in Shinto.
There are two redesigns of previously known SMT demons: Raphael and Omoikane. This is the new Raphael:
More info and pics on Siliconera.
Can't say I'm feeling these new designs, especially not the redesigns. In that Siliconera link, you can see the comparison pictures and I much prefer the older designs for Raphael and Omoikane. I will say that these look more "demonic", but I'm not certain that that's really necessary and I think they might be a bit too complex for their own good.
No mention of Soejima in the article or Kaneko, either. Wonder if it's because Soejima's too busy with Persona 5 or something. I believe Kaneko isn't mentioned because he's not working on SMTIV at all.