Well Coughlin is pretty well entrenched there for a while, being a pretty consistent coach throughout the years with several playoffs appearances under his belt (not to mention a Super Bowl win). In addition, Bill Cowher requires the freedom to bring in all his own people, which I don't think the Giants' owners would like very much. He's a great coach, but he just wouldn't be a good fit with the Giants.
Also lol @ your suggestion that the Browns will EVER win a Super Bowl :D
as encouraging as it is that Steeler Nation has spread to other areas, I'm a bit skeptical of former Cleveland/Cincy fans who "converted" just because their team isn't doing well. I dislike fair weather fans, especially ones that are willing to bandwagon jump to a division rival. I hate the Patriots too btw :D