They can get those extra iPhone sold easily. Apple knows how play the supply and demand game.
The iPhone is a completely different story compared to other products. It's just that good, that someone would wait an extra month when they could just get a new flashy blackberry right now.
You are right they do know how to play the supply and demand game. And they are much smarter at it than you are. No matter how good the iPhone is, as you put it, existing iphone sales would plummet if they announced a new version, with 3G and other hardware changes. It is also Apple's MO to not release any info on new products. One of the ONLY reason they did so with the iphone was the FCC documentation. Since those documents are a matter of public record, Apple had to be proactive with the announcement.
Its not gonna happen months in advance. Your wager is a sucker bet.