There was a rumor of this before. They said they were too busy to remake Halo 2, but would do it if they had the time. I don't see them making it any time soon if they're already busy making Halo 5.
I had a shitty Halo 2 experience. Lots of pop-in. If you played it on the 360 it wasn't there. My xbox was shitty and every time I played campaign, the disc drive would make deep scratches on the disc and I couldn't play campaign. I guess that's what happens when you take your xbox apart and not put it back together with skill like those sweatshop asians.