I would have to say that Halo will kill Crysis in sales. The hardware that Crysis is going to require is going to be nothing short of expensive. Console games usually sell better than PC games, consoles being the more easily attainable and require no hardware knowledge whatsoever. I think Rob was right on the money when he said it doesn't have to be a fantastic game to sell well. Just look at Halo 2, a piss poor sequel that added little to the story and added an extra gameplay element, yet it sold so well. Visuals were a bit better, but then we had that nasty texture loading delay.
I'm really hoping that Halo 3 follows the original's footsteps in terms of story and gameplay. I thought the level layouts were very well done, the story was pretty good, and the game was epic. I loved the open area wars that would occur in the larger levels.
Crysis, on the other hand, will absolutely kill Halo 3 in terms of visuals and gameplay. Story, well, I'm not so sure, FarCry had a pretty asstastic story, with unnatural voice acting, but what it lacked in those areas it made up for with visuals and gameplay. Would be my top FPS, if it weren't for the Half Life series. Kind of torn between the two.
FarCry just had fantastic level design, great for coming up with multiple strategies and angles for situations that occur in the game. By the looks of it, Crysis is going to be up there for visuals and interactivity with the environment, and it seems like it will be the same kind of style as FarCry. Definitely looking forward to it, especially if a Cooperative mode is included, or maybe modded to include it.
Unfortunately, Halo 3 will make more money, but hopefully the devs at Bungie don't take advantage of that, and release something worth playing, rather than pulling another Halo 2.