My dream is allowing teams to have anything that fits a box with 4(l)x1.8(w)x1(h) meters in dimension as long as it meets safety regulations. I want the cars to be shorter for two reasons: (1) it will take 20% less time to pass a car that is 4m long compared to the 5+ m long cars of these days; (2) a shorter car is harder to control and every driver mistake is more amplified, so it is more fun to watch them spin.
Any and every development is allowed even for the engines. The only limit would be a top RPM and top engine power (including KERS or any other aid) that they can't exceed.
Each team would be only allowed only three wing set ups (low-medium-high downforce) and aero setup all of which have to be homologated by FIA before the season. They can't bring a new component to every race. They could be allowed to implement changes a couple of times in the season. Allowing some development during the season will ensure that they will have a chance to recover if they start with a dog of a car, but in the mean time limiting it will save money.
And finally, instead of capping the expense, for every $ that each team spends (for development, drivers, races), they have to put a $ in a central reserve which gets distributed equally between the rest of the teams. So, if your team spends way less than any other team, the other teams are actually paying your team for their development. This will enable small teams to be competitive and sustainable. If Ferrari decided to spend $300e6 on their car development, they would need to put another $300e6 in the pool and each of the remaining 12 teams (assuming there were 13 teams to start with) would get $25e6. Not a bad deal...
Of course, these will never fly with FIA limiting everything down to the millimeter in every portion of the car.
Skeptical scrutiny is the means, in both science and religion, by which deep thoughts can be winnowed from deep nonsense.
Carl Sagan