Steve said "maybe we'll have a better idea". That's certainly leaves the door open for a fix other than a free case. There are too many posters here who are so "sure" there is nothing Apple can do with the design of the iPhone 4 other than nothing or a free case.
Or that better idea might be to just stop giving out free cases.
it depends on Apple's options. If the only improvements are expensive and/or involve significant redesign, then there won't be a fix. Lets all hope though the iPhone 5 is different at least.
My guess is people will just blame ATT for dropped calls and the heat will go off Apple. People will grumble, but people already grumble about the iPhone. (Flash, app store, ATT, etc) It will just be ammo for detractors, but in the end probably won't affect people who are interested in buying and using the iPhone 4.