In general, you don't want to fly in the transsonic zone (Mach 0.8 to Mach 1). The flow over parts of the wing goes supersonic, and while aero engineers can deal with supersonic and subsonic flows separately, we can't really deal with them together, the approximations flip (things go from being proportional to speed to inversely proportional). Most jetliners cruise right below the transsonic zone specifically to avoid this. The 777 uses specially designed wings to let it go further into the transsonic zone, so it can cruise at 0.85. If you design a plane to go any quicker either you need really long wings to lower the pressure differentials or to just go supersonic.
No, it's not, that's the point. Unless you find some way to fly without creating pressure differentials, a plane with wings that are miles wide, or a usable description of airflow transitioning from subsonic to supersonic, you aren't flying at Mach 0.99.
