I think of the thought process behind bones was
"Gentleman, do you like money?"
"murmers of yes"
"Well apparently full metal alchemist makes a lot of money"
"murmers of yeah that's true."
"So let's just make more of that."
Don't get me wrong I love the series too but I mean there is definitely a line where series should just stop. Like Bleach (Dunno why I'm still watching) or Zero no Tsukaima (Which can never have a real ending)
I mean I enjoy Bones they do good stuff Soul Eater is amazing, and I'm really enjoying Xam'd Lost Memories this season, I don't see why they need to make more of the same.
Will I still watch it, yes. Will I feel that at ever second I am being trolled by Bones, yes.
I've heard it will be following the manga but how they go about doing that is something I haven't heard (IE parallel, start off on a branch somewhere of the story)