It's going to be very costly when people start returning them due to poor signals. Do you really think a Genius is going to say this to someone's face: "Well, sir, you're not holding your phone right. You should really be holding it this way...". Good luck with that spin.
Yes, if SJ is willing to send a personal e-mail with that explanation if it gets to a point they'll say that.
The thing is this hasn't boiled over yet. The odds are that the average iPhone user isn't on a tech blog reading about it & posting about it on a forum. People have to start returning them and the press has to be consistently bad. If it reaches the same level of outcry we saw with the iPhone 2G price drop then the odds of a concession go sky high.
I think gethyphyyo has the right idea. If we see anything it'll be free bumpers. Either because Apple will issue a mea culpa or there will be some class action lawsuit. I just simply don't see a redesign coming from Apple.
This is a company that in the past has been known for always trying to wriggle out of warranty repairs for obscure or bizarre reasons.
I can't remember any off hand or find any immediately with a search (so I very well can be wrong), but when has Apple ever redesigned a flagship product at any point in the middle of a cycle? Even with the macbook problems back at the intel switch, I don't recall any in-cycle redesigns to alleviate known issues.