Assymetric reverse produces no more assymetry than normal engine out conditions if you think about it. It's not uncommon to fly the aircraft with two engines operating but one reverser locked out and use the servicable reverser on landing. The recommended landing speed with one engine out is the same as with both engines operating as is the landing distance, which is largely predicated on wheel braking and not thrust reverse. A hot brakes problem would only occur if you absolutely hammered the brakes on landing. In 1000+ sectors on the 320 I never came close to a genuine hot brakes (+500C) situation with fully servicable brakes, even with heavy braking