Spanky, that's why they have come up with the latest regs 'only the last 600m at end of straight'. So the horror scenarios you listed down can't happen.
Mate, I really beg to differ, but, even if we leave the passing aside, how does a faster car get away from the slower car?
Also, IMO, more than half a kilometer is plenty of room to pass, especially with the closing speed the drivers are describing.
Plus, remember this year the tow will be there but the turbulence from the DDD's wont be there, so car can sit far more comfortably behind another car.
Lastly, this whole changing it this late show how little everyone knows about how it's going to work. I think this above everything is my biggest beef. For god sake test it! If it's such a great idea, test and refine it at an appropriate level of racing - don't make F1 the guinea pigs!!