I think the answer is yes and no.
Here is my take, FWIW
First a hint that helped me keep straight which is which. 404c was voluntary disclosure to Participants. 404a is mandatory disclosure to participants. and 408b is the other one... disclosure to Plan sponsor.
Now to your question. 408 requires we disclose what we expect to receive annually. I think we can give the same notice every year, until there are changes.
404 requires we disclose what we received to the Participants and I expect the plan sponsor will always see this.
Anyone else have a different take?