Top speeds will keep on climbing, even if only for bragging rights.

Would dragster style parachutes be helpful for top speed records?
This way they can use more of the straight to accelerate as the parachutes will decelerate faster than using the brakes or some movable aero device.

"an NHRA Funny Car is slowed by a reverse force more than seven times that of gravity when both parachutes deploy simultaneously"
Fun facts

Thus they can brake later at the Ehra Lessien VW test track, BTW would VW allow to use their test track to test some (non VW) supercar to break the Bugatti Veyron record?
If not what other tracks can be used? Maybe the Edwards base 12 km runway?
Wouldn't salt flats slow down cars or make runs more dangerous?