I like the idea of an audible warning for the driver duriing a full course yellow, or when a recovery vehicle is on the track. Or making something on the driver's display be more visible. The screens on the steering wheels on some of the cars are big enough now. Have the whole background go yellow, that would certainly be an attention getter.
I don't agree with having something automated to slow the car down or disable the electric drive. These are F1 drivers, there's no need for something automated. Ignore the warning, get a penalty. 5 second stop & go, or something similar.
There's been talk now about them not being open cockpits anymore. I don't agree with that either. They've been open since the beginning. Close in the cockpit, and they'll have to put a/c in them for races like Bahrain, or Singapore, or Abu Dahbi. This crash was just a fluke. No need to close them in.