The only reason I can see Aaron's Avengers tie-in is because the Eternals and Celestials have been a big part of his Avengers run and this Eternals run definitely has spun out of his Avengers in some ways.
I'm curious to see if the X-Men are involved as well, given that Gillen is writing an Avengers/X-Men story for FCBD. Are these all leading up to just one story?