Here’s an idea for a possible alternative to DRS: resurfacing circuits to have different characteristics throughout.
The idea for this comes from Montreal. The biggest issue they have is the way the city freezes over in winter. Water naturally trickles down through porous asphalt, and when it freezes, it expands, which breaks up the surface. The solution was to create a less-porous surface to protect it from freeze damage. This created unique grip conditions.
So, surfaces could be resurfaced (when the work is needed) to alter relative grip. For example, traction zones could have higher levels of grip to help cars get away faster. On the other hand, braking zones could have less grip to put more pressure on drivers trying to attack or defend their position.
The advantages of this would be two-fold: everyone would have a level playing field at all times (rather than only getting an advantage under certain specific conditions), and it would clear the way for free use of DRS for all cars at all times, which I think would help address the problems associated with cars being unable to follow one another.
I’d also consider having a cool-down timer on DRS if it was unrestricted. It wouldn’t be anything serious, but simply a system whereby drivers would not be able to open their DRS slot for a certain amount of time – say, twenty seconds – after it has closed. This would encourage more strategic use if DRS: for example, do you use DRS down the main straight in Korea and then try to hold on down the long straight? Or do you wait and see what your opponent does before opening the slot? I’d also consider a system where DRS can only be opened for a certain amount of time before it automatically closes itself.