One thing that I did think would help make aircraft releases a bit less predictable would be to have manufacturers affected by the orders they receive on earlier aircraft (if this isn't done extensively already). I'm assuming here that the current data used for release dates, production rates and cost are based from the real-world information (I know some unpredictability is incorporated with the release date already) but surely all three of these things are massively dependent on the number of orders made. I'll try to give an example:
The production of the CRJ100/200 surely determined a lot of the facts about the CRJ700, how quickly it was ready, the production rate and the cost. If the CRJ100/200 was more successful on AWS than it was in real life, is it not more likely that the CRJ700 had a faster production rate, for example? I'm not a businessman but it makes sense to me that if Bombardier received significantly more orders on AWS than they did in real life, they'd have upped production for the CRJ700, perhaps with more funds were able to have it ready for orders sooner than they did in real life. I'd have also thought that if a manufacturer had absolutely appalling sales on a certain aircraft, it's unlikely they'd be releasing what is essentially a more modern version. So, in a highly hypothetical situation, if very few people ordered the A320-100 there's a chance Airbus would never actually make the A320-200.
The same could be said for engine manufacturers. If, say, Rolls-Royce were a 'more popular' choice of engine (perhaps by market share) on AWS than they are in reality, this could increase the probability of their future engines being more fuel efficient (not by a large margin, but even +-10% would force us to actually look and 'research' different aircraft types on the AWS world we're in before putting an order in - whereas at the moment, a lot of people already know exactly what aircraft they want and when they could order it) and subsequently it would affect the aircraft taking these engines.
It could make the whole system a lot more dynamic. Of course there are issues with the idea, and it wouldn't be straightforward to implement.