That's the thing with Hickman, everything is just set up for something. He wrote Sunspot, and did it well, for a few New Mutants issues, positioned him where he wanted and that's it. Now he just making cameos until whatever Hickaman have planned for the Shiar and Deathbird comes back. The problem is, it can be in 3 months or in 2 years.
Darwin was probably used by Hickman just to help the Children evolve, until they come out of the Vault with Armando's powers he probably will be remain forgotten.