Personally, I can't stand software thievery, but it really won't have all that much impact on their business unless it gets to the point of not having to solder anything. But that said, they still need to shut it down if they can to keep the publishers from getting all worked up. If publishers think that pirates will kill their sales, they'll leave the system. And that will kill it faster than anything. So they will need to make a show of it.
They will definitely care if a real mod chip happens since that will potentially allow cheaters on Live, and they won't stand for that.
I am sure they will implement bans on any modified box they detect on Live. Whether or not they can detect teh NME chip is a matter of guesswork right now. I suspect they will find a way to do it. It wouldn't surprise me if they came up with something that made it so if a mod is detected the system simply won't work at all.
If I were MS, I would come up with a detection scheme and do nothing until Gears of War or Halo 3 ship then come down hard.