"NamMyohoRengeKyo is the eternal state of Buddhahood, which materializes in any human being who is devoted to the Law. This interpretation regards both Shakyamuni and Nichiren as manifestations of the Eternal Buddhahood, and opens the way for all people attain the same state of Buddhahood. The eternal Buddha is the highest state of life, and can be manifested by men and women without restriction."
SGI's perspective, as expressed here comes eerily close to our own chart and includes our own interpretation of the Lotus Sutra. Maybe that's not too odd. But they still have a kink to work out. It's revealed in the following quote:
"Attaining Buddhahood is possible for all people, but each would have own [sic] mission and horizon of responsibility. We cannot be some one else or have a mission as huge as that of Shakyamuni or Nichiren, nonetheless a human being can manifest eternal [sic] state of Buddhahood through own [sic] mission in daily life."
http://www.sokahumanism.com/nichiren-buddhism/The_Eternal_Buddha.html
How could each person have his own mission if Buddhahood "materializes in any human being who is devoted to the Law"? Wouldn't their mission thus be "devotion to the Law"? Why can't a person have a mission as huge as Shakyammuni or Nichiren? Aren't all of us responsible for the propagation of Buddhism and the enlightenment of the planet?
The real reason they bring up "mission" is because they're trying to figure out a way to square their view that all people can be Buddhas on the level of Shakyamuni or Nichiren with an attempt to get everyone to follow President Ikeda. His mission is to be the mentor, and everyone else's mission is to follow. They use different language but end up in a similar place as other Nichiren sects: While everyone can be Buddhas, there is only one True Buddha. The only difference is that in SGI, it isn't Nichiren or Shakyamuni. It's the SGI Presidents.