Rule change will be the main thing to change chassis design.
The majority of chassis are 'similar' as they follow the most race proven layout to base a touring car on. The fact that they look similar from a casual glance means nothing. I can sit down with a 417 and an Xray and they handle very differently.
These cars are refined pieces of machinery, where every millimetre counts.
The awesomatix is a fantastic piece of kit, and I have a buddy who is loving his. But overall when you look at results, its no more successful than any of the current breed, if it was destroying them on the track then everyone would be looking at changing to that layout.