The other reason we cannot go beyond 12k rpm. Is none of our engine sound samples cope beyond 12k (we have no more samples to interpolate with). Some of the existing samples are already a bit harsh up the high end.
At some point, we are going to have to push the campaign end date out to a later year. But that will probably be Automation 2. We are not terribly big fans of DLC. We do have some plans for some, but it'll be more fluff, and hopefully collaborative with other people. The main reason is if you are late to discovering the game, there is this feeling of a big wall fo stuff. E.g. Civ 5 and it's 15 DLC's, and we don't want that.
Ideally we want a model, where for existing Automation owners, Automation 2 is a DLC like price. People coming for the first time will pay full price.
Bear in mind, this is way out in the future, we just need to have some plans in motion for keeping Camshaft Software a sustainable enterprise.