What does a next-gen engine look like? Well, for one thing, it needs to take advantage of the multi-CPU architectures. Scalable systems don't just happen, they're designed that way. I was lucky enough to give a presentation at Sony Devcon 2008 about how the Cell (and multi-core architectures generally) need to influence the design of gameplay systems. Designing your gameplay to work with deferred systems is an important step to scaling your performance with future platforms. I hope that this illustrates some of the planning that should go into place to eliminate "gotchas" when writing your next-gen gameplay code.