PJ2
Greetings
You have to realize that the brakes will not stop heating up, the temp will continue to rise, look at the brake temp after takeoff, and you will see that it is not 300 deg anymore. Brake temp will rise during the takeoff roll, due to the heat generated by the tyre's flexibility/friction.
Now after takeoff, the main problem is skydrol leak, leading to auto-ignite if the drop of hydraulic touches the brakes, in that case you will have a weel whell fire.(goto skydroll web site they published all temperatures)
During takeoff roll, if you need to abort, then, we have already lost 300 deg of energy absorbtion by the brakes.

Now the certification RTO was done with brake at .....
150 deg Look in the FCTM, you will see that Airbus doesnot guaranty a successfull RTO at max weights.