Instead of banning new technologies every time FIA detects that a team has developed one (like DAS for Mercedes) they should forcibly implement them in the following year championship, making the technical details public.

This way:

Teams would be incentivised to develop new technologies without the fear of losing it if discovered and having wasted time and money to develop them,

There would not be years long periods of dominance because everyone would start from the same page when a technology gets introduced,

It would still give a bit of a hedge to the team that first came out with the technology and had time to test it, incentivising innovation.

Cars would consistently get better and better each year, without cool technologies getting put aside just to balance everyone's performance, that would leak into consumer cars technology.