Yes, Apple will fix the antenna problem, if they want class action lawsuits and face a massive recall.........
Apple never officially admitted they have an antenna design problem, so how can you fix something that doesn't exist?
Do I think there's a problem? Of course I do, I hold my iP4 without a case and the signal bar will drop. So if Apple actually went ahead and fix it, or they don't admit it but someone (and I believe someone will) buys iPhone 4 from the new batch, and are able to find some HW differences, damn right I will ask for a replacement, and so will everyone else who has bought the earlier "defective" iPhone 4.
iPhone 4 still sells like hot cakes, I would just leave the problem as it is and skip the possible trouble all together, and I believe that's what they will do.