Happy Hangeul Day!
It's not every day that people commemorate the invention and proclamation of an alphabet.:)
Well, I am sure Duolingo will support Hangeul as we will need to use it to learn Korean when people make a Korean course in the future.:)
So I don't think it's foreshadowing anything. I think it's just an interesting coincidence that the release of the Incubator and Hangeul Day both fall on October 9th.