During the RTX 2014 panel an old halo developer from Bungie talks about his challenges with the map the map zanzibar(confirmed) and midship. It is kinda obvious that its returning since it is an iconic map and they decided to bring it up at the conference along with an already confirmed map.
-Midship
On this website take a look at the Halo bulletin 6.19.14.
“How’s backwash from Halo 2 running?”
“More musky and damp than you remember”
Bravo is definitely hinting that this map is being remade in Halo 2:anniversary!
If they remastered Backwash I wouldn’t even know what to feel. I’d be surprised and amazed at the same time. I personally have always loved Backwash, but I know it wasn’t a very popular map among the population (especially since you couldn’t even play it in Matchmaking).